Depending on where you live, it is foolish to try to register that Mustang with a FE in it. It would have to meet stringent emission control requirements, and would be costly. A 351W can be stroked to upwards of 440 cubic inches with the stock main journals. Transmission fitment in the mustang would much easier, EFI, everything. A FE in the truck would make it more era correct, and actually a better work vehicle if you decide to sell it. I have done several 351W swaps into the Fox/94-95 mustang bodies, and everything is a bolt in. The later mustangs are almost identical if you can get the wiring harness from a V8 for the swap. Joe-JDC