Engine swapping is fairly easy with a YJ depending on where you live. I swapped a chevy v8 into mine a while back and it was pretty straight forward, but I live in california and had to make it stock again to pass smog. It really sucks because the chevy engine bumped my gas mileage up significantly from my 4.2l POS stock engine, and the greater horsepower and torque were wonderfull. Just get the ECU programmed, any needed adapters (advanced adapters or novak adapters), wire harnesses, etc. When I leave CA, I'll put the v8 in again.