Roadrunner or Not

Hope the OP isn't swinging from a tree.

If you paid to much then go back to the guys who sold it and see if he will renegotiate. If not then lawyer up or tuck your tail and move on.

There are worse things in life than buying a hot rod that's not exactly what it was supposed to be. If you keep it then just drive it and don't get hung up on labels.

Take the stickers off and call it a MOPAR or a Plymouth B Body or whatever. It's still a nice hot rod and if you don't care nobody else will either.