Hey Glen,
Do your engine a favor and top it off with the latest and greatest in distributor options.
I had problem with my MSD distributor so i ripped everything out and replaced with PROGRESSION IGNITION all in one Electronic Distributor.
No more MSD box.
No more bundle of wires to route.
Reads manifold vacuum.
Down load the app for your phone and change your map on the fly while driving.
Greatest thing since sliced bread.
Ps: I run 48 IDA Webers! ( all i can say is WOW)
https://progressionignition.com/