DIM Electronic Advance Ignition

Re rotor phasing, my point (and 273Dart67's) is that the mechanical weight advance does not move the rotor tip relative to the tower. This isn't obvious and was argued before on FABO, but you can convince yourself by thinking about when the points open (or reluctor teeth align). When you lock out the weights and apply the rpm advance electronically, your rotor tip will move away from the tower. If too much, it may jump to the wrong cylinder (mis-fire), but you don't want the spark to have to jump far regardless. After-market distributors w/o weights are designed for this with wide rotor tips, as I expect the lean burn one must be (photos?).

I bought a new 8-pin HEI module as backup for $20. But junkyard first to get the connectors too. Any ~85-95 GM truck should work (small cap dist.). The advantage of the 7 or 8 pin HEI module is that you can easily command spark advance. As I recall, it is similar to the SAW square wave tweak used in Ford's EDIS (see Megasquirt).

Monitoring the ion current sounds elegant. It looks like you have been reading SAE technical papers.