I am a restoring. 64.5 Mustang Coupe with a 260 engine. The engine has all new internals and I fired it up last week and it sounds strong but will not idle. I have diagnosed it as a vacuum problem and removed the carb. The carb base gasket throttle bore holes are larger than the actual throttle bore of the carb and I am wondering if this is my problem. All sources list one gasket for all 2v Ford small blocks, and I am wondering if this is correct. I have attached a photo of the gasket. In all my rebuilds I have never had this problem, it this is my first 260.