Factory Roch B is the carb, note that most of these replacements happened along the journey, not just for this problem. Just pointing out what has been done that could be related.

Can't find any issues with vacuum, it definitely does better with the advance on rather than taking the hose off and plugging it, as if its working, and the gauge says it has plenty of vacuum so I think that is out of the way.

I have not dug inside of the dist advance, I will look into that. perhaps the old advance was seized up and the new one has the wrong advance curve causing both setups to give the issue?

It feels like its lean condition, though I cannot find any problems in the line or with the pump, it has 5/16 line, I have used different filters/no filter, it has good flow to the carb.

Sometimes when starting the engine cold, it will fire up strong, and then bog down and stall after 5-15sec, feathering in some throttle or giving a couple pumps will get it going for good. once its warmed up it gets better, and will always start up strong once its been running.

The accelerator pump squirts well.

I agree with carb, really it was very clean and it wasn't any trouble during rebuild unlike many that are seized up in lots of places.