Have you got any pictures of it.The engine number does match the VC-Sports number and it was made in 1977.Mark 4 would match the year.You are right with a remote primer there was no bulb on the carby.As for the one's I have pictured they are VC-Sports.There was a different variants of them.I haven't herd of what you are talking about so I would love to see some pictures of it.It does sound like a VC-Sports,Mustangs have different engine numbers such as 110,111 and so on.
