Couple of things...I've seen at least 6 68 B Bodys with SO's starting with a 7....seems to be a west coast dealership thing.I bet they assigned a block of SO #'s begining with the #7 to some Denver area dealers.It's pretty common to find a relationship between SO's and dealerships.
That incomplete fender tag posted above is one of them..WS23L8E117478....SO # 771508.
I've parted 2500 plus Mopars and have seen 2 cars that had a factory color change part way through.Parted one A Body that had a primered engine compartment and just colour blown over the fender edges.Mistakes happen.

S.O.#7xxxxx I have info on:
#726423 02/68 Charger 318 (Hamtramck)

#766440 05/68 Charger R/T 440 car (Hamtramck)
#767250 06/68 Road Runner HEMI (Lynch Rd.)

#771508 10/67 Coronet R/T 440 (LA)
#771598 09/67 Road Runner 383 (LA)
#772449 11/67 Sport Satellite 383 convertible (St. Louis)
#772811 11/67 Coronet R/T 440 BB1 & S6N (St. Louis)
#773832 10/67 Coronet R/T 440 JJ1 & S6N (Lynch Rd.)