1) yes
2) First part... no. Second part...yes if it is a pre64 receiver but you would have to likely set back the shoulder, rechamber, set back the breech face, and recut the extractor cut in the breech face.
3) don't know with out either the serial # or looking at it.
4) Don't know with out looking at it. But if it is, in fact, a pre 64 rifle then yes it will very likely be worth $450.