I've had good luck with Bob's F100s in Riverside CA. I'm working on the same sort of truck. They have a catalog that will show all the mount conversions - the 460 isn't supposed to be too tough.

Still, I'm putting an FE in my truck. The Shelby runs 10.6:1, with the heads worked over appropriately for unleaded and the timing set to factory spec, and it provides no trouble (other than in keeping the rear tires hooked up).

I like the FE, and the parts I've got look to be pretty good, so I'm working up the last bits (cam, intake, carb) to replace the 300 I6 that was there. Looks like a direct bolt-in, and the only trick I'm having to work through is the trans/driveline. I want to use the C6 auto, but will probably have to have a new driveline made for it.

The 460 advocates are probably right about resale, and there are a lot of 460 parts available. But the FE is right for the '65 truck, and that's important to me. Even if you start with a low-comp smog motor, the 460 works.

Had one in a gunboat T-Bird in the late '70s - a '73 Bird that looked like a Lincoln Mark IV. The smog motor still hauled that big trawler around pretty well.