Choosing the right carb for my car (340 4-speed)

Looking to see if this makes sense to everybody else.

When I was building my car, I bought a mystery 340 which turned out to be a pretty hot motor. It's got a pretty aggressive solid cam and a single plane Holley Strip Dominator intake. I have headers on it and a nice free-flowing exhaust. The transmission is a 4-speed with 3.55 gears in the rear.

When I bought the motor, it came with a Holley model 3310 carb, rated at 750cfm with vacuum secondaries (no choke). I had the carb rebuilt by my friend's dad, who said that it was a mess of parts but he said it should run alright.

Anyways, I've been driving the car for a few months and there was this really noticeable hesitation if I put my foot into it (even half throttle) under 3,000-3,500 RPM. After that point, it screamed and there were no issues. It also seemed to be running just a tad rich, though the plugs looked fine.

Anyways, I went to a buddy's shop last night to tune the carb a bit (it wouldn't idle well below 1,200 RPM and it was hesitating) and we ended up putting on a new Holley model Holley model 4776c 600cfm carb with mechanical secondaries (manual choke). We did a quick tune and the car now runs awesome. It burns tire through second gear and it pulls hard at low RPM, which it definitely wasn't doing before. I think the car being a 4-speed with minimal vacuum is the reason it responded so well to the mechanical secondaries.

I know I could gain more low-end by putting on a dual-plane (like the Edelbrock air gap) but I feel like this carb might be sized perfect for the motor on the street.

Does this seem to jive with what everybody else has seen? The carb and fuel line were over $600, but it's a local shop with a guy trying to compete against Summit and Jegs, so I don't mind giving him the money if the carb is right for the application. I mostly drive it on the street, so I think the 600 is sized better. I know the 750 might outperform it on the strip, but those times are few and far between.

Just looking to see if this makes sense. Thanks all for looking.

-Mike