The carb that you have was originally made for use on a Ford Pinto and a Chevrolet Vega, and was soon afterward adapted to us on VW's. I can't guarantee these numbers but I think those carbs were Holley 7200 and/or 7210's. Performance was great on the VW aircoooled motors, but every one of them required some re-jetting to get them to act right.
I think it might be a good time for an upgrade to a later version carb versus trying to rebuild and possibly playing the rejetting game.