Engine swaps tend to be a bigger job than most people expect them to be going in. Depending on the diesel and the amount of electronic controls you may need A LOT more parts than just the engine itself. Some diesel pumps will not even fit in the fuel filler spout of some gas vehicles which brings to mind issues related to the fuel system. Regardless of how good the job is it is likely some things are going to be rigged together to "make it work".
Yes I know people have done it successfully. My advice to you is to stay as far away from it as you can.
"Unless someone like you cares a whole awful lot, nothing is going to get better. Its not." Dr. Seuss
"Use peaceful means where they are appropriate; but where they are not appropriate, do not hesitate to resort to more forceful - Thupten Gyatso (the Dalai Lama, 1932)
"It is not the will to win that matters - everyone has that. It's the will to prepare to win that matters" Coach Paul 'Bear' Bryant.
"The ink of scholars is more precious than the blood of martyrs" - Muhammed