"Legal" isn't the problem. The problem is finding shops who will still work on old rims. If you mean you have wheel, bead rim, and lock ring, most big truck or ag shops should do those. Old shop manuals have instructions, but w/out big tools and bead breakers, pretty hard to do. Most of my old tires had to be cut-off with sawzall they were so rusted onto metal parts. Breaking that wire bead is hard. I used grinder discs on air tool to cut them. The wheels also have to be pretty rust free where parts go together. Sandblasting is best bet.
Are these the 8'lug? I found some 19.5" off a delivery van ( like bread or chip truck) that had same lug pattern. The 19.5's should clear any drum and still fit your truck. Mine was a 49 One-ton dually.
You can't weld the rims, then you won't be able to get tire over edge to mount them. These wheels don't have drop center outers to allow tire to fall into when changing, which is needed on a tubeless or one-piece rim.
Changing rear axles isn't too hard, it's the front that can't be changed most cases. Sometimes spindles went many years with no changes, and you can change back plates and hubs to newer style. 8-lug pattern went many years, all the same, don't think you should have problem. Problem is usually the rear large drums that won't clear newer tires. You can sometimes get 16" on front, but not back. Mine had Hydro-vac brakes, even bigger than stock drum in rear. 16" wheel didn't even come close to going on. Fronts were OK. These are dually wheels I am talking about. That's why I went with 19.5's. Not much out there in 18". Tires are hard to find in that size also. The new style 18's won't fit. You'll need tall and skinny size.
Good Luck!
