If the SSBC brakes are mushy and not air comes out of hte bleeders, it's time to pop the caliper off the bracket, hold the caliper at whatever funny angle you have to so the bleeder is the highest point, and open the bleeder until fluid comes out.
I had the same problem with my TSM kit. The bleeders looked to be at the highest point but a tiny bit of air was trapped above it. The funny angle gravity bleed fixed the problem.

As for the OP, was the size of the rear wheel cylinder considered when you ordered the MC?

We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon