I would do the complete opposite, 70-80'S mechanic in a new body/frame, i am fed up of rust but i hate modern over-complicated mechanic, if we don't have E-test in the near futur in quebec and my engine crap its pants in my jeep when the warranty is done, i would gladly adapt some kind of "big displacement" heavy machinery atmospheric diesel, like a 3000-4000CC inline 4 OHV All Iron engine with gear driven camshaft. That would be totally awesome. The hardest part would probably to adapt it to the transmission but nothing can be done with a bit of cash.
Those engines are kinda rare in the automobile world but are dime a dozen in tractors/bullzozer/skidsteer etc.