I know this is an old post.
I always assumed that my early 10/69 diecast must have had the tank replaced at the dealers as its non wrinkle, and the original owner told me it was like that from 'new' from the dealer. The fact that puzzles me though is that it had the 'Antimon' filler cap fitted and the riveted pivot part was peened over with no signs it had ever been changed (i.e. factory type peening over). Question is, would a new tank have a filler cap supplied with it or was it an extra part, as I think I have seen NOS tanks with the filler attached. If it was replaced and a later tank fitted surely it would have the later steel filler cap. The debate continues. I wonder why the tanks had wrinkes anyway, is it just that press forming a larger area than previous Honda tanks required that wrinkles be formed (largest Honda tank at that time was CB450K1 by my reckoning) .
Cheers ...Ash