Schumacher has engine mounts for the Gen III Hemi for a lot of cars, just not Fs, Ms, or J's listed as of yet I personally can't see why the A body or B Body mounts wouldn't work on our cars.
Biggest problems to work our will be the electronics and the fuel system. Fuel system pressure has to go up quite a bit, and there will probably be baffles required in the tank unless you go with an Aeromotive solution (the owne that uses a foam sleeve. Electroncs has to do with the powertrain computer, which control both the engine and the transmission, but also expects inputs from things like ABS and steering angle sensors. There are aftermarket vendors who work with this stuff all the time that can help out a great deal. If you get the transmission, you will a 5 speed auto, but it is computer controlled as well.
Bonus is a lot of horsepower, even stock, no worries about zinc content in the eingine oil, and a serpentine belt drive instead of multiple V belts. Driveability, once all the electronics deatails are worked out should be just like a modern car.
As for physical space, the J bodies can handle a big block with air and power steering, so a Gen III hemi is not a problem.
