I'll admit that "terrible idea" has a variety of meanings. From VERY terrible idea to "little bit" terrible idea. With a normal "bad idea" in the mix, too.
IF somebody tried to steer me away from doing something I'd read about, done on other cars, then I'd start doing research to find out why I was told that. THEN after doing my research, over time, I'd know why I was told that, possibly even discovering something better in the process. Research which included going to the popular car cruises, looking at cars, what had been done to them, and talking to the owners about their modifications. Noticing their tone of voice when talking about their modifications, in order to detect their enthusiasm with what they'd done, or otherwise. Then I'd also observe when they left and how the modifications affected how the car acted and drove off.
The Saturday and Sunday morning "Power Block" programming proved that "anything is possible", IF one has decent fabrication skills, backed by a shop full of metal breaks, welders, and cutters, among other things. NONE of it inexpensive, either. When many of us were 17 year olds, that sort of thing was usually only in race shops, to build race car chassis, bodies, and such. Places waayy above my capabilities to pay for.
One of the best riding/handling cars I ever drove was a friend's '71 'Cuda 383 with the optional HEMI suspension under it. A suspension which the magazines recommended against as it was "harsh". With its less sound deadening, it was quieter than our then-new '72 Newport Royal. There was one sweeping turn that had a washboard section to one side. My '66 Newport with HD shocks would side-step a bit on it, but that 'Cuda drove right through it smooth and flat, as if it was not there.
Body flex can be tricky. In the body design, there are some areas which are stronger to counter-act such flex, as others are designed to absorb it. Doing additional stiffening, up front, can do a lot to prevent later expensive repairs. I also DO know that Chrysler designs better UniBody cars than GM does, especially compared to the GM F-body Gen II Camaro/Firebirds. A friend noted "F-body" means "Flex Body". Sub-frame connectors are the norm on those cars if engine power and torque is increased very much. Not to mention on T-top cars. Sub-frame connectors would also benefit normal HD suspension cars, too. On my '77 LT, I also added all of the front sub-frame reinforcements to it, which did help steering feel a bit.
"AT tires", with their truck-chassis orientation, provide tire sidewalls which are stiffer than what we had back then. Tread designs and rubber compounds are better, too. They might look "different", but can be an incognito "performance tire" where normal perf tires are not built in that size anymore. Just have to get past the cosmetics on the sidewalls.
Weight removal can always signal a red light when a UniBody convertible is the car it is desired for. Convertibles already had stiffening in the floor pan to counter act the loss of the metal roof. The ONE exception was the '58-'60 T-birds, where a hradtop could be removed to make it into a convertible, with no additional stiffening needed as Ford over-designed that UniBody such that such was possible. As mentioned above, the best way to reduce weight in a Chrysler convertible is aluminum engine components (i.e., cyl heads, intake manifold) and even tubular exhaust headers. Only the very serious drag racers of the middle 1960s era "lightened" their cars (with acid-dipped fenders and a bit of Swiss cheese action), but then THEY had ready access to the OEM body designers to discover WHERE they could do that and not affect body integrity. Additionally, those cars were "throw-aways" rather than needing to last well past 100K miles on normal city streets and rough country roads.
The BAD thing about body flex is that it takes so long to appear, many times. Stiffen one part and the flex that part/area was supposed to absorb is transferred to a place that was not designed to deal with it. Which can then result in metal flex-breaks that must be repaired. Such breaks might be more prone on a non-C-body car because the C-body cars have more wheelbase length to absorb such flex than a smaller body vehicle does?
There is ONE thing I would recommend that ANY Chrysler Corp vehicle enthusiast do BEFORE getting involved in modifications. That is to attend the Mopar Nats and look at what others have done. It IS very possible that what one might be considering is there, so you can talk to the owners and find out what it took to do what they did (and you are considering doing). Plan on going for about five years straight, as what's there can change yearly.
It was at Mopar Nats that I discovered how deceptively EASY it was to put a B/RB engine in a '79 Dodge St. Regis/Chrysler Newport. In this case, the car started as a genuine police car (with factory dual exhausts). Only thing that had to be fabbed was the a/c line from the RV-2 compressor to the condenser. Everything else was "salvage yard" stuff. No chrome, just paint under the hood. Plus a LA-motor pie pan on a factory dual snorkel air cleaner. A great Malaise-era sleeper! He told the Chevy guys it was a 318, as they didn't know any better, except in a few cases.
One year, there was a high school auto shop class there with a 4-dr K-car. The car looked great in every nook and cranny I could see on the grass show field. The paint was "custom", but flawless. The custom interior was flawless. EVERYTHING was flawless. INCLUDING the Suicide Doors for the rear doors! Obviously, I suspect they took a worn-out car and completely remanufactured it, but added lots of things to replace the "stock" things in the process. Investing a huge amount of money in the process, but with a final product that was stunning and outstanding in the process. In many ways, "a terrible idea", but something that was totally unique and was an effective showcase for the skills they would use in the future to earn a living with. Their pride in the car was very evident as they prepped it for judging and made it look great. This was in the 1990s.
The ONE thing I really liked about the Mopar Nats was its INTERGENERATIONAL aspect. Lots of younger people with their cars, as there were grand-parents there to keep their grandkids while the parents were off searching for parts, cars, and other things. One year, I saw such under the Viper tent. By the convenience store near the end of the drag strip, I watched a high shcool guy put slicks on the front of his upgraded K-car, with a torque wrench, as his father AND grand-father watched nearby. I had never seen such at the many other non-Mopar events I'd ever attended!
When and if you do go to the Nats, BE IN SHAPE to be able to walk all day, non-stop, and then come back the next days and do it again. In 90 degree F heat and some damper humidity in the mornings. It WILL be enjoyable!
Enjoy!
CBODY67