[HO455]

I suggest that you find someone local who has a distributor machine and knows how to use it and have them curve your distributor. It is difficult to get a good curve by doing it on the vehicle. To many variables uncontrolled. The person who curves the distributor will want to know your rear end ratio and tire size, manual or automatic transmission, compression ratio, camshaft specs and manifold vacuum. If they don't want this information then they don't know, or don't care, so go somewhere else.
As much difference as you have found in the engine between the old distributor and the new one can be found just by having a properly curved distributor in your engine. In other words you still have horsepower on the table. Just need to pick it up.
Years ago (about 1988) after having recurved my distributor on the car I happy with the improved elapsed times and though I was done. Long story short pulled the distributor had it curved. Nothing was terribly wrong with it but once I dropped it in and set the timing the very next pass down the strip was 2 tenths faster in the eighth mile. Now it was a 12 second daily driver. and it got better MPG too!