You know I always read about MSD ignitions not playing well with their timing lights. I use a Snap-On digital with my MSD 6AL all the time without any trouble at all.
My digital timing light has a built in tach and I can also dial in how much advance I'm looking for.
Their not cheap though I think I paid about $350 for it 15 years ago
Gus


64 Plymouth Savoy
493 Indy EZ's by Nick at Compu-Flow
5-Speed Richmond faceplate Liberty box
Dana 60