The only sporters that were factory d/t’d were the C models. They were d/t’d on the front receiver ring and rear bridge. None of the sporters were factory d/t’d on the barrel, except for maybe a special order.
There is always the small chance that the rifle could have been special ordered with provisions for scope mounts, however without some factory documentation such as an invoice or receipt, it is pure speculation.
That said, I cannot imagine Winchester ever milling the receiver bridge flat to mount a scope.
Steve