Still hesitates off throttle...

I have been doing all of this testing with the air cleaner off. The mechanical advance springs are in good shape and everything is lubed up and moving freely.

I think I put a bandaid on it for now though. I went through the carburetor again and didn't find anything, but I did change two things. The first is that I put a bigger main jet in. It was a random jet that I had in my parts bin and it is not stamped so I don't know what size, but it is slightly larger than the 552 jet that was in there.

The second thing was set the float slightly higher than it should be. The dodge manual I have says 27/32" or 0.84" wet height which is what I had set it to. I double checked it before adjusting and it was still there. I then adjusted it a hair and it is now about 0.80" while idling.

The problem now is that it is clearly running rich because all I did was just richen the entire rpm range and didn't actually address the low rpm stumble... hence the 'bandaid'. Probably wasting a bunch of gas but no more hesitation and it seems to be happy. I also set the timing back to 5 btdc.

As for the vacuum at WOT, I have no idea why, but it is definitely there.

I will get a jet kit so I can more accurately tune that.

I am not convinced that I actually found the culprit, but I am going to call it good enough for now until I have more time to tinker. Could have just been the float level and the main jet change was unnecessary. I will report back when I figure it out. Thank you all very much for your help!