I am experimenting with an HEI unit on my 302 GMC. An excellent source you might want to look at is :
http://members.aol.com/dvandrews/timing.htm It is titled "Ignition Timing for Modified Engines". It talks about deternining static advance based on cam duration, establishing maximum advance based on combustion chamber type, it gives a typical advance curve for modified engines, it explains how to modify the advance mechanism range and rate of increase to get to the desired advance curve. I think it will help you.
Hope it helps
