WRT the Edelbrock 750, they have some known issues which sometimes to often cause linconsistancy but mostly in the high speed system. I'll find the threads where this has been discussed.
This summerizes the two big differences in parts between the way they were designed (Carter) and how Edlebrock makes them:
1. Booster is too short for the venturi.
2. Cluster may have any of several versions of well tubes. AVS2 800 carbs
