I'm with Steve, do we really need to reinvent the wheel here?
Langdon's mini-HEI offers all the advantages of the Mallory unit, including a "canister-type coil" and Tom Langdon is a 'bolt "guru", offers great technical support, and is a pleasure to do business with. I've been running the mini-HEI for over 2 years, works flawlessly.
The article makes no mention of how, or why, "adjustable" advance is adjusted, or even needed. The GM engineers built the vacuum advance parameters into the HEI (admittedly for a V6) and I trust Mr. Langdon to tweak those parameters for the Stovebolt 6.
