Ended up going for the GT185 tank. It has a few advantages:
- the Suzuki Savage petcock is an exact swap.
- said petcock fits without modification as it clears any obstacles on the left side and sits between engine and choke lever pretty much perfectly.
It also takes the LS650 front tank rubbers.
Also I wanted to be able to have passengers and therefore wanted a smaller tank length wise so we have little more arse room.
Yep the GT185 capacity isn't great but is actually a shade larger than the Ryca tank so I'm sure it will do as a round town bar hopper.
Following in others footsteps (Dave's) with slight variations, used the old tank mounting points and the old seat mount to create a holder for the GT tank hook. Works great: