Seems to me you've been fixing this thing up so it runs properly (carb and ignition repairs)- what does the vacuum guage show? If you have some cooked umbrella seals and loose valve guides - the motor will suck all of the oil it can - right down beside the stems. Many motors run more oil to the rocker shafts on one side than the other too. Makes that bank smoke more.
Consider doing a valve job. I don't know which heads you have but....bucks down....get these gone though and some new rubber covers in there. Won't be too bad a job for a couple of guys to take the top end off and tote the parts to the machine shop. At least it won't be the full Monty.
Or......do some serious looking for a set of decent replacement heads - the 113's or G's would be nice if you can get a line on them. Spend the valve job money on what must be a better piece in the long run.
Steve Metzger Tucson, Arizona