Not sure what your question is.
I have some documents here that were given to dealers in regards to engine numbers matching for certain models for the series 70's.On the top of that document 1 is for Cortina.
Not sure what you are talking about with the muffler.I didn't say anything about that.
In my 2 copy's of the Green Book the carby's part number is listed as the same number as the G2.
Which was also the same as the same year model Corvette that I have which also has the G2.
I'm not the one who is an expert on carbys (unfortunately he doesn't come on anymore)but you will find there isn't many sales brochures that list the G2,I guess they didn't run them for very long,one could even say they are rare.Maybe they had problems with them (I don't know),but I can assure you they did exist.I even had the same model with one,but unfortunately it wasn't worth saving.