I had a 510 through the 80s but don't ever remember replacing points or even opening the distributor. I suspect it was electronic ignition. But I have not problem with points and condensor on most of my other old iron. 40+ years since the 52 Merc had the points replaced and it runs fine. Co-incidentally I was working on the distributor of the John Deere AR tractor that has sat in the back of my shed for over a decade. No spark but all it took was a little sandpaper over the points to clean off the oxidation. Finished off with a piece of newspaper and voila! Spark on both cylinders and I soon had it running. Video coming up on the yt channel soon. My uncle used to replace points and condensor and spark plugs as preventive maintenance on the tractor back when it cost less than $5 for parts. 
https://youtu.be/ksK9HgK1tss#mce_temp_url#