This sounds correct. Charlie would never and has never used power toms.Answer is in Steve's remarks. He said the toms came from a kit Gretsch gave to Charlie to use for Charlie Watts Orchestra appearances. This would have been in the mid-late '80s; by then, Gretsch certainly was offering the 10x12.
I believe Steve also DID borrow drums from Charlie's black nitron Stones kit at other times. I recall reading that and the RB pic above seems to depict that. That's a different kit.
So I think we're really talking here about two different black Gretsch kits of Charlie's, both of which were borrowed from by Steve.
In direct answer to the OP's question, you're looking for '80s 6-ply.