With all due respect Norfolk, Winchester model 70 collecting (like Parkers, Colts, LC Smiths et al) has nothing to do with anything a British gunmaker or dealer could offer. Value is based upon rarity and percentage of ORIGINAL condition. Rook is absolutely correct. That rifle could be a cool $1200 shooter (as a shooter I think it beats $800 just because of the caliber.) If it was actually built by Winchester in that caliber, but has subsequently been "freshened" by lightly redoing the stock or even adding that pad three days after it left the factory, it is a 1.5 to 3K gun depending upon how badly a collector wanted an extremely rare but "ruined" rifle. If by some miracle it is in fact original, and it can be proven to be so, then the sky's the limit in a specialized auction. I should also offer, that Winchesters of all sorts of rarity have been concocted by everything from shade tree butchers to brilliant craftsman who make painting forgery look like a hobby.
I have just such a beautiful resurrection in my gunroom in the form of a Model 94 take down rifle. It is just about a perfect, and shoots beautifully. It is a 94, it is a takedown, but it isn't original.
Rule should have known if any were made, but, indeed, he likely would not be able to actually authenticate it without having it in hand.
Did you try these guys?
https://winchestercollector.org/ You will likely have to join to get a meaningful response, but they were extremely helpful with a two barrel Model 21 set that I own (discovered it was original in spite of wildly different barrel serial numbers).