That's a good point. I'm going to make up a cable that goes from that stud bolt to the starter mounting bolt, just to give an alternate ground path if something happens again.
It was about $160 to get the rebuild. I gave the guy a ballpark for a new starter and asked if he could get in the same range. There's a lot of gravity in that Lucas starter, and I figured if it was good for 45 years, it would be good for that again with a rebuild.
Having said that, the only new ones I saw before were off brand Chinesium, not Bosch, so I may have made a different calculation if I'd known that.