Fred, keep checking on ebay and at the junkyard, there was a guy selling 16x6 199? F*rd van wheels with a 3 3/8 backspacing. His auction said they were the ones to fit on early Chevy trucks and he provided a link for the clips for the hubcap. I just looked on ebay, but don't see them right now. I also think truckandrvsupply on ebay had some of those wheels.
They weren't real cheap (about $100 a piece), I thought I was gonna have to go this route on the 53 one ton before I found a dually setup.