BSA, above has a significant flaw 'nailed.' The stock has been cut, likely for a recoil pad and a 'half-vast' restoration as removed & altered butt plate installed. The net, net, the stock is ruined as collectible component. As yet utilitarian perhaps, the term "Truck gun" comes to mind with the caveat probably length of pull short at about 12.5"or so!
The metal looks good, but quality photo and lack of coverage, major assessment impediments. A pix of my Prewar Model 70 SN 31K, below reflecting the proper - untapped receiver view from atop. Bridge holes only on left side to facilitate receiver sight installation!
The matter of "true" or altered barrel to achieve carbine length, "messed with" seems less likely. The effort to alter professionally typically not spent for common chamberings such as here, in 30-06. Of course, never say never! Believe the proper length barrel measurement is rod inserted into bore. From "bottoming to center of muzzle; at 20". Good to have a headspace gauge as indicator "by suggestion", of whether the barrel is original to the rifle.
These Winchester major components as well as lesser ones, subject to 'mix & match. Properly accomplished, not to waste time fretting. As crude alterations occur at collector realm prices, there's the rub!
My take & good luck!
Best!
John