The Leeds system MIGHT work well for some other brands of cars, but the track record for C-body Chrysler vehicles is poor at best. As documented in many threads in here over the past years.
ONE thing to consider is that if a big box national hot rod parts place sells it, does NOT mean its a good system with good parts in it. Looks can be deceiving, too. If the price is very reasonable, then consider that they are making money and then move backwards to suspect what they are paying for it. In another forum, there is a thread about an HEI distributor that is sold with all sorts of colorful language ("custom-curved", "all new items", etc.) at a reman price, which failed right out of the box, as other name brands lasted decades. Even after putting new electronics in it, it was of poor durability and performance. FWIW
Is the master cyl in the kit a real C-body Chrysler power disc brake master cyl? Perhaps what is on the car can be replaced with the genuine item?
Personally, I might "over-shop" some things until the real urgency to spend that money is past. Realizing that what is on the car OEM is really pretty good stuff and went through a rigorous testing activities before it was put into production. Of course, as time has progressed, newer and better things have evolved, which can produce upgrade possibilities. I also understand that as newer/younger people come into the hobby, they have grown up with disc brakes and consider anything else as inferior when it really might not be, just what "they know" or know how to work on. I might know some things about EFI, but I also know carburetors and points ignitions, which is what I grew up with. I DO personally like electronic ignition systems, IF the electronics are good and meet OEM durability levels, or higher. BTAIM
HydroBoost can be a great system. My experience with it on 1980s GM diesel pickups proved that it had a more solid pedal feel than the vac boosters did with power disc brakes. The longer-term issue was booster leaks in the floorboards. Getting the hoses loomed in a better manner would help clean up the underhood area, I suspect. Of course, the power steering pump needs to be large enough to handle steering and stopping at the same time, but GM and Ford OEM items are available for that.
A cleaner alternative would be the GM PowerBoost booster, which used an electric motor to pressurize a "pressure ball", but it was troublesome and the PBoost system was usually replaced by the HBoost system.
Just some thoughts,
CBODY67
