My understanding, Winchester didn't make any 7mm chambered barrels postwar. The metric chamberings all "pre-war creatures. Rifle in question, the topside chambering marking near the receiver, an earlier marking location. While correct for the carbine barrels, possibly not so such location for the more common standard length 70 barrels even of prewar> Seems to me, the chambering stamp should be with main-group nomenclature forward of the barrel sight boss. Critical, that barrel should be wearing an integral-forged ramp. If not, believe it's not genuine on that count without having to seek further!
Lesser 'certitude', but I also think that most all the "barrel clean up guns" were actually made up in the latter forties and most, even marketed into the fifties, were on receivers with the 'elder' cloverleaf tangs. The early postwar barrel clean up guns were cataloged. The '54 bunch, I believe were uncatalogued and primarily wholesaled out to Winchester distributors - but that a 'shaky' opine!
I could well be wrong concerning this, but comporting to my recollection having read it in Rule or possibly Whitaker's book. Because my thoughts here are not set in stone, I wouldn't want to disparage that pending sale. Simply just expressing my doubts. I'd sure want to do further research before bidding! My one solid point, the integral forged front sight ramp inclusion critical!
Just my take!
Best & Keep safe!
John