I have a MSD Billet dizzy locked-out with a 20 tear-old 6AL. I tried a MSD start retard box. It worked, but I noticed the timing retarding as rpm's increased. I read somewhere that it's a common issue. I removed the start retard and the issue went away. You may want to consider a fast crank with a separate ignition switch.
Get the engine cranking and then turn on the ignition.
Powermaster makes a starter that's designed to crank at a faster speed.
Your results may vary.

I also needed an adjustable rotor to clock it at the tower. Go figure. I may sell the bunch and go crank/cam trigger with CNP.