Yes - an Enfield P14 - needs a huge barrel shank diameter to thread to that action, 1.25" IIRC. Thus, it probably did not come off a different action- appearing to be full action diameter - standard shank length ahead of the action.

"I suspect that this was a receiver/barrel that was dropped into a sporterized milsurp stock and had a new rear site put on it. If the barrel had come off an enfield action it would need some work to go onto a P14 receiver?"

Yes, possibly - but the barrel would have had to have been threaded to this action to start with, seems to me, due to it's dimensions.