Following the Run of the VC-160 & 125, the VC label was continued onto a few new mowers in 1973 (the VC-160 Was dropped) this was the replacement for the VC-160, the VC-Mustang, and the new Mid-Range, the VC-Sports.
The Mustang has had a number of different releases, the first few, 1973, 1974, 9175 and maybe 1976 it was labeled the VC-Mustang, later the VC was dropped, and it was called just Mustang.
The first one or two VC-Mustangs had the G3 Metal Carby, then it went to the G4 Plastic, the first of witch had it facing backwards to let the air hose in, the next year however, it was turned around, and a hole has made in the cowl to let the hose in on the other side.
if you are looking to go within the VC-range and make the full VC Family, i would start by tracking down the 1973 or 1974 VC-Mustang's, the ones with the metal carby.
Don't worry about putting to much effort into hunting for a VC-Mustang of the later times, with the plastic carby, they are fairly common, and one will crop up without to much effort.
Pop up some photo's of the head and I'll let you know if its good for the job.
I'm not sure about the bases, but i will look over the ones i have tonight.
You are looking for the mustang with the same air filter and throttle control as the VC-160 (in White)
The plastic carby uses the black one with the air filter and control in the same unit.
I'll try and dig up a photo for you.