Timing issues...backfire through the carb is too advanced, through the exhaust is too retarded. Since yer headin to the distributor, look at the points. You say it hasn't run in a while so points could be corroded and a piece of sandpaper and a reset could solve this also. Everything else being OK, IE, carb, points, timing, put in a new condenser. Good luck and let us know how ya did.
