Sounds like a slick project. A couple of notes though:
I think boxing the frame is overkill. These use the same frame as a short wheelbase 1-1/2 ton, 137". They *can* get loose rivets in the front cross members when run overloaded over rough ground beyond the limits of the suspension, in which case one can burn off the rivets and drill the holes to take 7/16 bolts. I know this from personal experience. Fixed 25 yrs ago and all is well since.
Because of the heavy frame and long wheelbase in my opinion these make lousy hot rods. I've not seen any suspension kits specifically for 1-tons, either front or rear. That said, you could take the front cross member and independent suspension, hubs, steering linkage, etc from a IFS 3/4 or 1-ton. I don't recall which era those trucks were, maybe post 66 for a few years. I have looked at them in wrecking yards and they're always missing the sheet metal so I didn't pay attention to the model year. Doing that would give you IFS, a steering box (likely power), motor mounts for a V8 and some frame stability for when you eliminate cross member no. 2 to clear the V8 bell housing and transmission. It wouldn't be a bolt-in but a good welder should have no trouble. I've seen this swap done to 66 and earlier pickups to get the better IFS. I have few suggestions for the rear suspension and axle but if money is no object maybe you could use independent rear suspension from a late Suburban. I think the usual hot-rod stuff is too light duty.
