Surge problem at speed

I have been struggling for a month or so trying to figure out a performance issue. I have a '67 Dart with a 360 LA engine. I had some electrical work about 6 weeks ago due to massive drains on my battery. During the work the distributor got fried. The shop doing the work replaced the distributor (ignition switched to electronic ignition 6 years ago). Since I have gotten the car back the electrical system is great, but when I accelerate heavily it sputters kinda like it is not firing correctly. At speed on the highway it will surge periodically, almost like it missfires, then it is fine. Literally just a quick misstep, then all is good. It seems to do this less at 70 miles an hour, which is about 3k on the tach. I found some gunk in the carb, cleaned and rebuilt the carb, still sputtered, but better. Finally ended up replacing the carb, filter and fuel pump, and still sputtering. Took it to a shop and they changed the spark plug wires, still sputtering. I am thinking that the distributor that replaced the one that got fried is not firing correctly. I am thinking about switching to one of the Petronix billet distributors to see if that fixes the problem, or should I be looking elsewhere? Any help would be appreciated, or I have to break out the blow torch.