I have a rear swinger from a GSX1200 Inazuma in my katana, going to put a 170 tyre on there because it gives the chain more clearance, so won't have any chain run problems, and still have a fat tyre.
Also have an aircooled 1100 with stock swingarm, also going to use an 170 because the 180 that is in there runs against the chain and the frame..