I know I know it sounds like a big waste of money, but I installed a DUI HEI distributor (at the cost of 320 dollars!) in my 64 Tempest wagon with a rebuilt (326 +0.060) motor with 9:1 compression and 068 cam.
It has been one of the best upgrades ever- 26 degrees in the distributor all in by 3000 rpms.
Car had a cheap $70 swap meet special HEI (Proform/Procomp?) and it worked for 1500 miles marginally at best. I thought I had a carb problem- bad accelerator pump- because of a stumble off idle. Then the ProComp module went out and I decided to do it right with a recurved for the motor/cam HEI.
Car now runs like a fuel injected modern car- no stumble, pulls hard through all gears, cant wait to see what my mileage is gonna do. Feels like it picked up 10-15 HP. Nooooo regrets -will do it again for my 454 66 Chevelle...