I agree, the cream plastics could have been original to that era, but unless it was a special order, it didn't leave the factory with them. Also, I don't think the pickguard is a factory Gibson pick card from that era either.
That being said, it was an extremely popular mod in the 70s. Frampton and Frehley both come to mind.
If you like the guitar it certainly isn't a deal-breaker at the price although I would try to get them to knock $100-$150 off if you plan on replacing any of the hardware.