I would lay odds on it being a plugged strainer or clogged H speed circuit. Metering diaphragms usually gives more trouble at low speeds doe to stiffing. If not then crankcase vacuum test for bad seals or could be a bad ignition coil.
Usually when I get in a 2C that needs fuel lines or broken built in primer bulb I pull the carburetor, disassemble it to the cube (removing mixture screws) and toss into my ultrasonic cleaner while I am replacing the fuel lines. If gaskets and diaphragms are still in good condition I reuse them if not I install a carb kit. To me it just waste of time not go ahead and clean the carburetor while I at it for if I don't I usually end doing it anyway. Don't forget to set metering lever to the correct height.
