First track run - less than exciting....

I had the same issue with my carb setup, glad to see I wasn't crazy. I only had a little 525 cfm AFB on mine (carryover from the 318 that was in the car). Best carb I've ever dealt with when it was on the 318. You could fire that engine up and drive it right away without having to wait for any kind of warmup, regardless of the weather. However, I had the same issues with quick full throttle stabs making the car fall on its face. Flat to the floor would kill it, but lift just a touch and it would take off like a rocket. Quick rolls were okay as well. Messed with several jets, rods, and springs, but was never very happy. Started looking for a mechanical secondary carb without much luck. Ended up trading some leftover pistons for a Holley 650, but I'll give you a word of caution now. The Holley I got would not work on the ModMan stock. The linkage on the passenger side hit the top plate during travel. You'd have to run a spacer to give you the clearance you need, on my setup as least. Not sure if all Holleys are the same, but you might try to borrow one before you buy one to test fit.