I'm beginning to understand the purpose.
Now it just gets to the details.
If I were building this car, I would do the following for getting the Hemi into place.
We can do simple first. Big block version of the 727. Have someone good build it. You'll need the 8 bolt flex plate. All your mounts are gonna be off the shelf Mopar.
Engine mounts are going to need to be fabricated. I'd have something close to the stock type done, mounting to the stub frame. Use a rubber stock type mount as a solid mount will shake every bolt loose. Forget the elephant ears, this isn't rocket surgery, hot rodders have been making mounts for decades.
Assuming you can still buy repop exhaust manifolds, they would be the ticket as Hemi manifolds flow like headers and would be easiest to work around power steering etc. Exhaust becomes custom made, but that was a given from the start.
I'd look at an aluminum radiator, they are making a decent bolt in for a 440 that would all bolt up, assuming this car has the larger rad opening that is. Not a big deal to make it bigger if if doesn't. Just have to match the bottom location with the water pump and again that's already done with the 440 and all the water pump etc bolts to the Hemi so no big deal there, just a little homework. The vendor here, whatever their name is, would be a good source for a rad and could tell you the locations on their rads without any of the usual hysterics.
You can pretty much wire it with a stock OEM harness, thus avoiding the Mickey Mouse aftermarket crap that was copied from a 68 Chevy Nova. I'd keep the stock alternator/charging system and not let anyone try to sell me a 1 wire GM alternator. Again, the Hemi shares 440 brackets although I think the lower pulley might have an extra couple bolts, but I don't remember. If so, all that is shared with the b and e bodies, so that's easy to get a repop version. Stay with the stock belts too it's more impressive to see period correct hardware if you are building a period correct car.
So there is my take. I've purposely left off details about the engine build and just concentrated on getting a stock configuration Hemi bolted in. The only "not off the shelf" bits are the motor mounts and a guy that's good with a welder can knock those out after lunch. This would also let you build a fairly stout engine, as there's tons of street/strip cars out there with the engines bolted in just like the factory did it.
From there, you can plan the engine build. I always give this advice. You need to coordinate cam choice with converter with rear gear ratio. People seem to fall apart in that one. Less is always more.
