Chip I found this link that pictures the SSI, the SSII and SSIII rims all together. The description you gave about the smooth center cap sounds like the SSI but in '72 the wheels were SSII with the painted inserts a grey or a body color and the center caps weren't smooth. The SSIII were chrome plated and didn't have the outer trim rings. Then there were the SSII wheels used on the Delta cars which had a different center cap altogether. I think you car should have the SSII wheels with chrome outer trim rings, non-smooth center caps that bolt in and the little stainless trim rings around each of the five holes.
edit: oops, forgot the link,
http://images.google.com/imgres?imgu...%3Den%26sa%3DG
edit: I don't think those are actual original wheels shown but copies, pretty close though.