You are correct. I have MSD AL-3. I normally run locked out. With this build I decided to check out playing with timing. Right now initial is at 20* total @38* The 20* seemed a little high to me. But from what I am reading lately with my cam and compression that is normal. I do have the blue springs in.
20 I think would be just about bare minimum. You have a 18 degree stop inside your distributor? What is your cranking compression? How did you come to 38 being your sweet spot?...