Perfect Roger, thanks!
That answers another question I had...can the fender be moved forward or backwards on the bed side an inch or two and not have the outside edge of the fender intrude into the wheel indent. Answer is YES!
Also, DV. Your option is a good one. But, it might be less work and easier just to buy an F1 Rolling chassis for $400 and swap everything over, then get the F1 aftermarket box and put it on. I mean seriously, the truck is really nice and the body is in super shape (question: Front fenders fibergalss?). Also, what you talked about is very do able. There are beds on e-bay every now and then that are really reasonable.
But to close the loop on just replacing the fenders, can you possibly measure your 53 fenders where they mount to the bed? Here is what I'm thinking....If you are only talking about an inch or two too tight in the back you could probably move the F2 fenders forward and no one would know the difference. Or you could get a pair of F2 back fenders and take 2 inches out of the center of them...no one would notice that either. It all depends on how much bigger the F2 fenders or as compared to the F-100 fenders.
You have a lot of great options with the truck!