My truck has the long 161" wheelbase and I will put a 10.5 to 11' bed on it. The bed is slightly shorter, less overhang than the probably 14' original bed. The width will be just a few inches wider than the rear wheels, so about 7' 6". I remember measuring an 05 crew cab long bed F250 and my old 48 is essentially the same length and width, even though it has duals and the modern pickup has single wheels. Around here a crew cab long bed truck is normal, which is why I was saying you don't have to do much to an old AD farm truck to make it fit where a modern pickup fits. These AD trucks are already reasonable small in comparison to modern stuff. Narrow and shorten the bed some might be plenty.
Did you understand the suggestion of only running the inside dual wheels as some earlier model trucks did, what do you think of that? If so you could narrow the bed even more. While it may look odd at first it is not unprecedented, so with the right bed details it could look right.
I think you'll find gear ratio is more important than you realize. A stock 1/2 ton can do well over 50, and a stock 2 ton will be screaming at 50. 6.17 axle gears even with approximately 33" tires will still make for a slow truck, not comparable to an AD pickup truck.
I'm not sure which single piece wheels with the 10 lug on 7.25" bolt circle you have in mind to run radial tires on? The easy and cheap option are modern 19.5" wheels from a P30. They may or may not fit over the brake drums depending on the size truck. Other options are hard to find old 22.5" wheels, probably not cost effective to find some, restore them, and then sell the truck.
I am and was trying to help think of solutions to the obsticals you have presented in your plan to make a big truck almost as appealing to someone looking for a pickup truck. What I see so far is it won't be easy/cheap to properly address the goals you have outlined.
As already mentioned probably best to let each individual buy, build, and or modify their own truck to suit their needs.
Grigg
