COP Ignition Development
You may have mentioned this, but it helps during cranking to delay the spark timing to TDC or even later. That way the cylinders don't fight the starter. I recall that Holley's Commander 950 does this. If the sensed crank speed is <500 rpm, the controller assumes the engine is cranking and delays the spark. Also, to get a stable idle speed, the spark table usually needs a "saddle" around idle. Otherwise, you can get surging where as rpm increases, it gives more advance which makes the engine run faster, ...
You probably already know that you can get a cheap mini-starter by using one from a V-8 Magnum engine (~1990 - 2000 trucks & Jeep GC, perhaps even V-6). I put one in my 1965 273, but also fits slants and BB/RB engines.