A p-14 or P-17 in any calibre other than original .303 or .30/06 is not a converted gun, but a custom rifle. As Steve said, depending on who make it, it could be worth as much as any custom or simply rebarreled military rifle - or as little - much depends on the workmanship involved.

They make good rifles in any calibre and if in good shape will handle any modern round. Those rifles/actions have been the basis for big custom rifles for decades.