Paul,
How are you ? So the new carb is no good. Ok that said I can help you id what you have. Can you post or email me a picture? I have a bunch of original Autolite 2100's (The carbs that came on 2bbl early v8 Mustangs).I think I've mentioned this before But I build/rebuild original Ford carbs for people. If it makes you feel any better I think that the Autolite 2100's(I;m not a big Holley fan) are the best carbs ever made for the small block Fords,That's my own biased opinion of course.