Engine swaps are for people with way too much money and or time. Plenty of people will tell you have easy the swap was and how nice the results were. My favorite is a local guy that really had me going for a bit, then I asked him, so what kind of work do you do ... race car fabrication with a full shop at his disposal for projects. Yup, piece of cake.
I don't think the early 944 trans auto or stick will handle the V8 power, most people start with a turbo (plenty of cheap blown motor rollers around) or better an early 928 with an auto.
More info at,
http://www.porschehybrids.com/php/