There are several factors that dictate how much initial timing you can/should run. It really boils down to how much your motor can stand and the distributor set up you run. Starter kick back is usually do to to much initial advance.
Most iron headed pontiacs like total advance at 36. The amount of mechanical advance will then determine what your initial advance will be to achieve that.
For me I have a converted points distributor (Daves small body HEI) and I modified the oval limiter with a set screw. I also have a RobbMc starter after struggling with hot start problems. I run at 16° advance and 36° total. I run my adjustable vacuum can at 10°
Your best bet is to get a pen and paper, grab a timing light and do some recording. Disconnect you vacuum advance get your idle as low as possible and record your initial timing. Rev the motor to about 4500 and record your total timing. The difference will be your mechanical advance. From there depending on the distributor you run you can plan your next move.
