10 inch rear drums ????

Get ahold of whitepunkonnitro (user here on FABO). He may still have some used ones left. Finding nice used is pretty much your best bet at this point, or wait to see if some new ones turn up on ebay again. I got the last ones I saw pop up on ebay that Oklacarcollecto pointed me to and paid through the ear for them (but they were made in Canada, so at least not Chinese).

The only reason I wanted to keep SBP on my GTS is because I'm trying to keep it as close to original as possible (the drums won't be of course), but honestly, any other car, I would just upgrade to LBP axles & brakes and be done with it. SO much less hassle in the long run for brakes and wheels. Then I'd go to 15" wheels for same reason. Even 14" tires (that look okay on a muscle car) are getting hard to come by anymore.