An opinion:
I put a hand built oak flatbed on a '78 Ford 1/2 ton.
Since the rear tires were over-sized, I measured the distance
between the top of the axle at the spring mount and the bottom bump-stop under the frame. I built the platform so that
the distance from the top of the tire and the under side of the
bed boards was an inch greater.
I would have been better off if I'd added another inch I discovered when I accidentally was overloaded to the extent that
the tire rubbed against the bed boards. Seems that the load was riding on the compressed bump stop!
I was lucky in that I was on smooth level paved road from when left the quarry to where I off loaded.


Restoring an old Chevy truck is a mission for people who just need a few more problems in their life.