Couple of guys have done mkIII transplants i think
Issue #1 no manual box from factory,if you want a manual there was a place making replica diablos that sell the bellhousing adapter between W58 and 1uz
then you will need flywheel and all the associated goodies for it
Have to figure out if the computer wants an auto box input and find a way around that (as i wouldnt be connected)
Issue #2 engine mounts, you will need new ones custom made no doubt
Issue #3 You will need a front sump for the MA61, is it a front mid or rear?
I wanted to do this for a bit as does JUSTCALLMEFRANK, he can tell u why its the cheapest to start with but most costly in the long run!