Minor nicks and scratches on the stock won't affect the value. The percent original finish remaining is the determining factor for condition.
In order to appraise a pre-'64 Model 70, you need the production year to determine the class, since there are three classes; pre WWII, transition, and pre-64. You also need the model, the caliber, and the grade.
Different Models are: Standard, Featherweight, Carbine(rare), Target, Varmint, African, and Westerner.
The Model 70 was offered in many calibers, from .22 Hornet to .458 Win Mag, with some calibers available in only certain models.
There were standard grade and super grade models available.
I'd suggest starting with the Blue Book of Gun vaues for a basic idea of what it's worth. Also, any non-factory alterations will substantially decrease the value.
Appraising Model 70's, like a lot of other old Winchesters and Colts, is very complex, and you REALLY have to know your stuff.