hi thats a really nice pice when i got mine i clould not beleve how heavy it was !
That would make your gun a original Upgraded model, most of these Lithgows were refinished in the 1950s, if yours is a FTR then it will have FTR and a date on the left side near the barrel lock nut. If it hasnt got the markings then its a little more original. I also know number A9488 is still in the UK as a deac.
ATB, Chris.
p.s. heres a list of known Survivors near yours
A9375
A9482
A9488
A9491
A9570