Ditty, I will tell you something about the 460 in that truck! That was an AWESOME motor! I saw a stock one spin the tires at 50mph with little effort! Althought I am a HUGE PSD fan, I am a FORD truck nut in general! That would be a tough decision for me to make. When I was a kid my father also bought a 8000 E250 11 passenger van with a 460. Stock that thing would do over 110, because my father and I pegged more than once! I would have been afraid to get beside that thing today, if it were in new shape! The new 460's are not much, but the old ones were dooseys!
I LOVE the late 70's f series! My first truck was a F250! 351M Granny Gear - Dualed exhaust, and rims! I LOVED that truck. I ocassionally still dream I have it!
good luck on the project.
Bob!