Another guess my SB 340 et 1/4 mile :)

Before you do anything, put the light on it and turn the distributor so you have 20-24* at idle. You'll likely have to close up the throttle plates as you add more timing because the idle speed will pick up. As you turn the idle speed back down verify that it still has the 20-24 timing you set it to start with. If it drops out, add it back in. At some point the mix screws should start to have an effect and engine will shut off when screwed all the way in..

On the MSD, put the 18* black bushing on it and one of the light silver and light blue springs. Toss the garage door springs it comes with in the bag... :)

If you want a limiter bushing that allows for more initial timing, I have them in both 10 and 14 degree versions.

The stock electronic distributors can work. They just aren't set up for anything with a decent sized cam.

I've fixed tons of cars that run just like your right now. Takes time to get your ignition timing set up well but it will tear it up once correct.