Welcome. ORD is making the swap brackets for the 2WD to 4WD conversion. It may save you some time. They make crossmembers too. FYI your rear spring hangers will be shorter than the 4WD drive versions (FYI C20 3+3s are 1-ton versions, not 3/4 ton). Photo 1 is my '85 K30.
Photo 2 is my old...