This is an old thread so the problem is likely solved by now... but for the record... figuring out the correct timing when the distributor is "all in" is a very small portion of properly setting timing.
Any fully maximized tuning will require changing springs to adjust ramp rate and optimization of idle timing for best off idle response.
a fairly typical chevy sb with a typical distributor and typical cam profile will typically do well using the 34-36 at 3300.
thats a whole lot of assumptions and generalizations. Ive written a few very long detailed posts here about optimizing timing through all rpm ranges. not just the top or "all in" and not just the bottom or idle.
basically I sent the bottom end at the minimum advance to achieve peak vacuum then use various springs to adjust the ramp rate to achieve optimal perfomance.
the vac advance is intended to add appx 15 degrees of advance when the engine is not under a load, ie cruising. this is strictly an emissions/mileage enhancer without any real detrimental effect on performance.
