I installed an 84, 5 litre HO Mustang V8 engine with the 5 speed manual tranny in my custom 76 Pacer. It was not that big of a deal.

The Mustang oil pan was perfect for the project and fit like a glove. I made custom motor mounts by combining the Pacer mounts with the Ford mounts. I also installed a nodular 9" rear end out of a Boss Mustang. It worked well when all done.