Let us see how you mounted the "pretty tank" when you get a chance
Here you go
The tank is a later model from (I think) an R90 and I think the seller said it was from an '86 model. The front mount is the same as the R65, but just a tiny bit wider. I just shaved a bit off the rubber and it went on fine. The photos show the rear mount which took a bit more playing around.
Photos
1. Is the mount. Found on ebay, imported from the US for $22 (a small fortune in Australian dollars with the exchange rate the way it is)
2. Shows 2 threaded lugs I had welded to the frame - nice neat job
3. The mount on the frame. Just using 2 allen head bolts. This mount needs some rubbers which I have to order.
The tank has a strip underneath with 2 holes, so you just drop the tank on and fit a circlip either side - see photo 1
Cheers