70 442,rebuilt 455, HEI Petronix distributor. Just got car back with rebuilt engine. How can I get the most out of the timing,mechanical advance, and vacuum advance. It is set to 12degrees base timing,8 degrees vacuum adv,and was told 32 degrees total. using the springs for the mechanical adv that came w/distributor (has 2 other sets of springs)I want to experiment to get it running the best. Not sure if the vacuum adv is good at 8? Guess my question is how do you know what the vac advance should be at, and also the total degrees, and if I should be using the other springs in the kit for the mechanical advance? Thanks in advance.