Greetings Don, and welcome aboard.
Congratulations on the purchase of your Model 12. The only Pigeon grade models I've seen were trap guns, and they all we all marked accordingly. Winchester made some very nice Skeet guns that weren't Pigeon grade.
Is this M-12 your quail gun? I depends on how well it fits you and if your quail are taken close enough for the Skeet choke. If it isn't, then I'll be happy to swap you it for a brand new M-500 or R-870-Ex.
Your assumption that the fore-wood is a replacement sounds plausible. Of course, it's more likely the factory wood may have been re-contoured with the finger grips (my preference) and the factory checkering lost. Does the fore-wood match the butt stock? You can always have it checkered if it bothers you.