Still hesitates off throttle...

Sounds like my 1969 Dart slant. It would stumble off the line and sometimes die when leaving a stop light, which was embarrassing. I would drive with both feet to goose the throttle so it wouldn't die. I also had to fool with the choke setting between summer and winter, since I didn't understand the choke pull-off then, thinking it was a damper. No internet then to ask and learn.

I dealt with it for 18 years, trying 3 rebuilt carburetors. I long suspected a vacuum leak and even tried a different manifold. Mechanics said "valves", so I had the head rebuilt twice. Finally, when same issue with a new long-block, I tried a 4th carburetor and it purred like a kitten. The Holley 1920 has a sealed metering block which gets clogged (idle metering circuit) and most rebuilders don't touch it. Some here said they know how to blow it clean with an air nozzle. I no longer have that car (stolen in 1994) and my current 1964 Valiant Slant has a Carter BBS which works fine.

One test for running lean is to close the choke plate by hand (or just partially cover the top inlet). If the idle smooths, you know it was running lean. Of course, installing an O2 sensor, especially a wideband type, is the ultimate diagnostic. Forget looking at spark plugs since that only indicates the average O/F, not conditions at idle.