a more exotic swap

If you want to try to put a stealth 4 banger in from Mitsubishi, feel free. But depending on what you are trying to accomplish, If it is 4-wheel drive, like said above, you could do the Daimler Donated AWD technology in the 300's At least then you can bolt it up to new style V8 or V6.

Personally, I wouldnt want to deal with either of the two computers and working out how to computerize the simplest A-bodies out there. Go from 3 wires to the engine to 50, Plus the trans, plus the AWD, etc. Sounds like a wiring nightmare. Doesnt sound much fun. I like mine simple.