Before we assume its a "drafted pistol" we should have pics, because in theory it could also be a military 1911a1 lower, with a civilian slide aka parts gun. The markings mentioned by the OP are standard for a commercial "government model" whereas a US military 1911a1 slide will not be marked that way (the slide markings changed several times since the beginning). If its a drafted pistol, then the slide could be perfectly original, but I think there is too little info right now to say for sure.
AFAIK, the slide should serial number to frame, which would end all debates about what the gun could be. The slide would be marked with the SN under the firing pin stop.
Winchester 73, the TFL user that won the west