I am actually in the final assembly stage of completing this swap, I used a '90 300 with EFI. The biggest issue I ran into was the length of the engine, keep in mind I did a lot of other modifications at the same time (front axle 5" forward, doubler, etc). To get the 300 to fit I built new motor towers to mount the engine on, removed the front clip and built a tube front and "massaged" the center of the firewall some with a BFH. I have a bunch of pics of the install if you're interested in seeing anything in particular