It was a mech MSD dist. After about five years the distributor would get all rusty and built up with crap. Plus they're not cheap. Have been running an HEI (vac adv) in my 68 for longer than that without any issues. I put another in it recently because it's a shoestring build compared to the 69 and I was pleasantly surprised on it's performance.
I was kind of thinking the same thing Dr. (after nothing else was working). Usually careful about those things but you never know. It does purr at idle and only start the ping at about 2500 rpm. Since I tried timing points from nine down to about three degrees, wouldn't I get it right eventually even though I'm a degree or two off when I dropped the dist?..
Not too familiar with total timing Bob but always willing to learn something new. My light is adjustable.