I forgot to mention that I do get some popping through the carb on lower revs.
I think Skip was right on the money with the overlap.

These cams were meant for higher Revs. (Not for street use)
I see the problem disapear with higher revs. My habits have to change. I always liked the chugging sound with the lower revs.

 

These days, due to unleaded fuels, it's very difficult to get a meaningful fuel mixture indication from a spark plug.
They almost always look lean, unless the motor is *extremely* rich, or burning oil.

The only sure way is to spend some dyno time, using an exhaust gas analyzer under loaded conditions.