Well, well... if you want to become a Mosin-Nagant expert too, first drop that "i" from the name!

Now, for that Westinghouse as for any other collectible, it all depends on condition: if the rifle has been left as-is with no drill&tap, no strip&varnish job, that's a good thing.
If the barrel condition is great, that's a plus but if the barrel is dark because it was shot with corrosive ammo it won't sell well with shooters; a collector will tend to pass over that fact if the piece is a rare one, but the offered price may be less than for a shiny barrelled one.
Can you or your friend take some good close-up pics of the rifle, incluing buttstock (both sides), action (same), barrel root, front and rear sight, etc... ?
Post them here with a description of the markings found and you'll know in short order what his rifle is worth.
If you want to know more, PM me and also go to these links (I put two spaces after http: to prevent hot-linking):
http: //7.62x54r.net/
http: //www.mosinnagant.net/
See you soon!
PP.