It's been a long time since I worked on an old Carb but I do recall back in the day this was sometimes caused by the accelerator pump. There was a little leather type cup it there and if it failed you'd get a flat spot on initial acceleration. That pump gives a little squirt of gas at intitial acceleration. If it doesn't you gat a lag, or flat spot. I don't know how to describe it but it will be on top of the carb probably on the bowl section. It's possible the bowl isn't filling all the way due to a stuck float.
This all from memory. Like I said it's been a long time.
But before I'd do anything drastic I'd check the Idle adjustment. Idle adjustment might also cause it and so can a faulty advance mechanism
BillinNashville2010-07-07 06:42:54______________
It has been over a year since I started. I had to quit the project so
the car just sat in the garage. I was able to get started again in May 2012. As of July 27 2012 I have done the fiberglass repairs and applied Slick Sand High Build Primer.
https://www.c3vr.com/member_uploads/14401_14500/14470/Doors-off-(Copy)201261111476r.jpg
