Years ago I met a guy who stuffed a Chevy Vortec 8.1 into a Jeep TJ. It was impressive. However he had a lot of heat issues.
He ended up using a couple of small 12v fans to help get hot air OUT of the engine compartment. It really helped.
Now one thing I want to ask, is this on a carb'd vehicle or a EFI vehicle? Because on an EFI vehicle, you should be able to "flush" the evaporated fuel out and get clean fuel in just by running the fuel pump for a few moments. However on a carb, you are screwed.