you can try bennet or kumbac but all the cally owners steal the cally interiors and 6 speed transmissions... both these places probably have waiting lists for them :P but no harm in trying
One dude (Simon a.k.a SimID) paid about $1k for leather interior but that required a bit of effort to get in coz the base of the drivers seat was bent from the impact and the door cards were damaged and he had to chop and change bits from the stock to the turbo...
The leather interior only came on the Cally T in australia, and i saw a thing with the numbers of callys that were exported around the world... and this thing reckons there were only 134 cally Ts (excluding private imports) sent to australia... i think that might be an underestimate... but it would probably be better, cheaper and easier to get them reupholstered.