Hello brewsky,
You can get Rod/big end + shims/crank pin kits from a few sources for around £90 GBP (you'll need 2). Similarly with main bearings. I woud use genuine Suzuki crank seals as they are still listed by Suzuki. One US based crank builder, Bill Bune, has a pretty good reputation for his work. Pistons are available from Suzuki, Mitaka (cast) or go up market and fit Weisco or Wossner (forged). A full engine re-build for a T500 can get costly, but I guess that's not unusual for any engine. The crank in Gary's bike cost him £800 GBP (pork chopped, lightened, all new bearings/rods etc. Luckily the Suzuki main bearings are very robust so if the have not suffered rust will only need a swap out of crank seals.
Cheers Geoff