I'd try to strip the existing stock. Oops, I didnt notice the "sporter look". That "7.62x53" is interesting as I know of one country that uses that designation with ammo, and allegedly they made a few of their own SVT40 barrels....
Could you elaborate on country of barrel manufacture. I assume you are referring to Finland as the 7.62X53 caliber marking. I haven't found any other markings that might lead to Finn capture or origination. This gun in fact is AVT-40 as I test fired the gun past weekend to check select fire operation. And it goes full auto.