Classic over carburetion problem?

Ok I ran across a car a while back that had that exact part installed in a 66 273 with a solid cam that was supposedly rebuilt in a shop near here. The shop apparently did not know how to set the tappet lash and the engine ran fair but would lurch at low speed. I was told the engine was a 318 by the owner. So I assumed it had hyd tappets, I did a comp test and all seemed to be even but a bit low. So we thought perhaps a valve grind might be in order. Later on the covers were removed to pull the heads and that's when it was discovered it had adj rockers and the valve las was too short. A warmed engine ran worse. We adjusted the valves and comp was still low. Valves got redone comp came up and once we got that distrib properly calibrated, WOW I wouldn't have believed a 73 could make that much power but then I thought about those old D stockers at 275 HP, same as the factory rated 340s later on. Anyway the 73 was too quite before, couldn't hear valve tapping. That's why I originally thought it was an 18 with hyd. not a 73 flat tappet. So point is look closely at the igniter no matter what model or make, they are mass manuf. and there's always a chance for issues, which is a big reason nobody makes distribs anymore.