I use an old analog Snap-On dial back light and it works very well with my Firecore distributor and MSD 6AL box.Now with the MP electronic distributor and the MSD the timing was erratic by 5 degrees both ways
Gus

6932018-mysavoy.jpg (84 downloads)
64 Plymouth Savoy
493 Indy EZ's by Nick at Compu-Flow
5-Speed Richmond faceplate Liberty box
Dana 60