After a few years of modifying my driving style by compensating for the acceleration bog, I've finally solved the problem! And boy is this a relief!
I tried all sorts of things, checking the timing, advance, looking for leaks, adjusted valve lash, MHCV operation. All of those things I probably needed to do anyhow (after the valve lash, the engine REALLY quieted down, sounds awesome). Finally, after a long drive (1900 miles round trip) for Thanksgiving, I decided to just do a rebuild of the carb because my needle valve was stuck open at one point during the drive.
Orderd a kit from Daytona Auto Parts (Kit 440A). Cleaned things up, swapped everything out, reinstalled, and engine started, but it had no idle. Decided to just go for a drive understanding that everytime I came to a stop, it would die. It would restart fine, as long as I kept it out of the idle circuit. BUT, during the drive, I realized there was no longer an accel bog!! Good strong punchy acceleration at all speeds! FINALLY!! NO BOG!!
So two things. First, the reason I no longer have a bog is because I finally have the correct accel pump shaft length! For all of you who have similar accel bog issues, I suggest you look at the length of the pump shaft. My carb needs the shortest round accel pump shaft (can be found and as described in the Walker parts catalog). 64-70-1; 1.292 inches long. What I had in there was the longer version, 1.398 inches long. I had no idea, and Daytona correctly sent me the shorter version without my asking. I feel confident that shaft length was the issue all along because while trying to trouble shoot the idle issue, I reinstalled the old accel pump and the bog returned, although it idled just fine again.
Second, the accel pump that Daytona sent me had one of the idle air-bleed holes misplaced in the gasket. The holes in the new gasket misaligned and covered one of the air-bleed holes in the carb, and thus no idle circuit. I didn't realize that until taking apart the carb multiple times and blowing out the passages. I finally decided to look at the holes in the gasket, and how they lined up. Voila! Punched a new hole in the gasket to line up better, reinstalled, idles like a champ. I informed Daytona about it, and they wrote me back and said they mistakenly sent me the wrong accel pump, and will send me the correct one at no charge. Not sure if I'll replace it now that the one I have is working fine, but we'll see. Here is a picture of my old accel pump (the one that was causing the bog, but idled fine) with the correct hole location indicated:
So all of you who are getting carb rebuild kits, check to make sure the holes line up correctly before you button things up. What a relief to finally have the car running great........