My experience with old truck ignition modifications:
- on a 235cui engine I used the Pertronix 1168LS (compatible with Delco distirbutor). This worked fine and was easy to install. If the rest of the parts are in good conditions. From this view, HEI was not a option.
- on a 228cui engine with 6V system I tryed a Petronix, too (for 6V) but with this i had temporary starting issues so I came back to points.
- on my actual 292cui engine with HEI distributor I had to change the integrated ignition coil but I can´t say how old this coil was. After this the centrifugal advance parts where worn out and the vaccum advance was sticking. So I set up a chinese reproduction HEI distriutor. This works fine for the moment....
