If you want to go with an HEI swap, I'm just about to change over to a mallory distributor, and have an HEI module you can have for free. Only been in the truck since July or so. I've also got a stock coil I'm parting with as well.
Just make sure to re-time the distributor when you do the HEI swap. Depending on which way you wire it, it will swing about 10degrees of ignition timing.
My oil line fix
My 100k stopped odometer fix
Brace for impact, I'm in a "modifying mood". Massive thread count inbound.