outside of tire measurements are potentially misleading. the 4x4 boards i'm on use wms-wms numbers, which eliminates the offset and width of the wheel. wms = wheel mounting surface
i've kicked around taking axles from a more modern 4x4 to convert my 52 3/4 ton too, and one of the issues is spring perch width. the frame on the AD is different width than the donor axles, and the donors are wider overall.
something else to consider is the end use of the truck. if you want to go wheeling, the travel before hitting the bump stops is pretty small. for just tooling around and the odd fire road it won't be an issue.
