Mild 318 misses at 3000rpm

You are probably getting a reman smog unit that probably has 28 to 30 mechanical built in at least.
Try setting your initial at 5 and work from there to see if that corrects your missfire prob. You really dont want more than 34 degrees total with todays pee pee fuel.
It is worth your while even with your light mods to get a decent adjustable distributor.
Contact Trailbeast. He can hook you up with a great setup on the cheap