Twolane those mags are pretty solid in my opinion. You can clean up the armature and put some new brushes in it and should be fine. If the armature has slop in it there are paper shims that can be added on the ends around the bearings. Pay close attention to the finalic (fiber material) gear/ advance unit. If it is decaying or missing teeth you will want to replace it. Not a cheap part. When you set the timing I always used a zig zag rolling paper in the points. With crank set at 39 degrees before top dead center, turn the advance unit slowly open. Hold tension on the paper while turning the advance unit. When you hit wide open the paper should just be released. I would also set valves. Intake .002 and exhaust .003. Turn the motor over until rocker arm in at top position for each valve and then turn Thur again and recheck each valve until they are correct. These are the basics and will get you going. I would take that carb. off and soak it in some zep. or strong chemical and check jets for obstruction.