$365 for an assembled megasquirt 1 that will do full timing control with what ever distributor and ignition coil you already have and a few other things. Like datalogging boost, AFR, intake air temp(s) etc. Will also do standard and 2-step rev limiting if you like. I've known multiple people that have used MS just to control timing, leaving the carb in place.
The MS1 panel, the MS2&3 offer A LOT more, but it only matters if you plan on using the other options. But here are the basics for spark, rev limiter, 2-step launch control (set hard cut for spark instead of fuel), and over boost protection.
Here is a generic spark map, everything over 100 kPa is in boost. The ign advance goes from 26º down to 19º as boost goes up.
