Replacement tank kz440

Hi folks, does anyone know what tanks can fit a kz440 (I have an '81 C model - not imported into the US) and my old tank rusted out.

I have not been able to contact the local restorer whom was supposed to be fixing it for the last few months so I figure it will be easier to get a new tank.

At the moment I just want to know what tanks might fit, so I can look round the local jumble sales.

looks the same as a 550 tank i have here in seattle.

easier to get a new tank than to go get the one you already have? go kick his door in!