Great you got the electrical sorted out and running. Is it smoking badly or why do you think its burning oil.? I would definately do an oil change and check the compression with throttle open and then put oil in the cylinder just a little bit, check again and see if the compression goes up. If it does worn rings.. When oil gets old it gets thinner and contaminated with condensation and possibly gas leaking into sump from poor carb needle seal. Its also possible that the rings may be a little stuck from sitting for a few years and that will get better the more you run it. Generally running rough is fuel and air related not always but the first place to look. Is the the original Mikuni or has it been replaced. I would do a thorough cleaning of carb, which you may have already done, but remove the emulsion tube to make sure its clear, junk seems to grown in there and can only clean it by taking it out. I would check the valve clearances and make sure they are in specs and then run it for a while and see if it gets better.