https://www.summitracing.com/parts/c...00-1/overview/
I recommend one of these. Use the two blue springs along with the factory HEI weights. It is best to limit the travel of the advance arm to around 1/8 of an inch. I do this by tack welding a plate that acts as a stop. This will give you about 12 degrees vacuum advance. Your HEI should provide 20-22 degrees mechanical advance assuming it hasn't been jacked with. Set initial timing to 12-14 degrees at low idle in gear. experiment hooking vacuum advance to full vacuum(only if you limit the travel) or timed(when vacuum is only applied after the butterflies are cracked open. 32 degrees total (initial+mechanical/all in around 3200) is all you want/need with the combustion chamber shape of the Vortecs.
Been setting them up a long time like this and they haul if everything else is right