its not as terrible as you think. the transmission wont be pulled with the motors. just the motors themselves. i have a friend of mine who is a master mold maker with Mosler automotive who can make an aluminum bell housing adapter that matches up with each block.
the only thing i will swap out each time are the blocks themselves, the ECU/wires(which will be tucked/organized for easy removal/install) and fuel system minus pump/psi regulator.
the car is an 82, so its not like its got all the different wires/electronic devices that require wires like cars do today.