Random HEI shut off

Have a bit of an odd extremely intermittent problem going. Have a LA 318 with a GMC style pro-form hei distributor. Every once in awhile the car will just turn off like key was turned off. No stumble or rough running, just an instant ignition cut. It'll instantly fire right back up no issues and won't do it again for a week and then randomly do it again. Always at just above idle as I'm like pulling through a parking lot or yesterday as was pulling away from a light. Any ideas on what should look around for to see why it's doing it? Would like to be able to fix it because becoming slightly annoying especially when decides to do it as you're pulling away from a stop light lol.