Did this hesitation manifest itself before or after you rebuilt the accellerator pump / carb? Just trying to narrow down the possibilities here. It sounds like you have a Carter AFB 626 CFM there.
Sounds about right - it IS a Carter carb. I bought the carb and rebuilt it, from what the previous owner has said, it did not do this before I put it on my car. And seeing as he sold me a strong motor with no problems for 75$ and a few other parts that are exactly as described I dont think he screwed me over on this carb.
The timing has been checked and I believe it hits 38 degrees total advance at WOT and at idle its around 10 degrees. Base timing is fine at 5 degrees BTDC.