Here is a link, from a Buick website, about Petronix vs. Points concerning nailheads. http://www.teambuick.com/forums/showthread.php?5482-Pertronix-vs.-points&
I would suggest a distributor rebuild that consists of a through cleaning and polishing of all working parts. In rality thats the best service you could do. The delco unit in your car is the best ever made but gets gummy and rusty with time etc. There is nothing really wrong with a good set of quality set of points ( CS786 NAPA )and they will last a long time. The pertonix will add some longer maintence periods and they work very well ! They install right in the old distributor.
I did the Pertronix & coil upgrade on my 55 Special, my 54 nailhead powered roadster and a friends' 55 Super... all work perfectly and better than the points did. Quality was noticeably better on all 3 cars but my roadster was the most improved in ease of starting, idle and performance.
Pertronix units install in the distrib. and don't change the orig. look at all...works super ! I also added a Pertronix coil to the INVICTA. JK www.legends.thewwbc.net
I know he said HEI, but these days when most people say HEI they are merely referring to electronic ignition. There is no HEI available for the Nailheads, but there are plenty of electronic options if that is indeed where he wants to head.
Everyone has an opinion---here's mine. I grews up in the '40s and '50s and watched our local hotrod scene pretty intently. What I saw, or what I thought I saw were guys always trying to find an "edge"--to go faster, farther, more dependably. A V860 is better than a four--an 85 better than a 60--and now, WOW a 100 hp flatty. Whoa, a small block chevy--see where I'm going. To me, traditional says innovative, progressive--you pick the word. Reactionary does not fit. Not trying to start (excuse me, continue would be a better word) argument; just one man's opinion.