Man, you guys have some gorgeous cars! I appreciate the responses; funny that the only Duster so far is Cab's which is a very different animal than this car. I saw one Duster with 325s under it (!) but the guy didn't know the wheel size or BS.
Once I get the diff, axles & drums back in it I'll re-measure everything for the 5th time and maybe even fab a cardboard example to try to only do this once. Pretty much gotta go 15x10, just need to nail the BS.