If you're still looking, I may be able to help you out. Have a 77 CB400F tank I was going to use for a cafe project, but it's not going to work and it's too nice to modify to fit. Tank is currently stripped to bare metal and has had 3 small to medium dings filled with LabMetal, so it's ready for paint or powder, as you like.
Photos of the tank here: http://www.vinmoto.org/gallery/v/VinMoto-Garage/CO-OHVinMoto-Garages/cooh-gmkieran/XS750/During/Tank+Work/
Asking $140 + shipping. Hit me up here or at gmkieran@yahoo.com if you're interested.
Cheers!
GMK