I can’t answer your question of putting a “value” on the referenced extraordinary rifle.  Yet some comments. 

The Blue Book at its best, most accurate range for common model guns. The more extraordinary/exotic, the less well to provide accurate info or, as you note, any info at all. Classically too, in the pre Internet connected world, a part of attained value very much related to getting ‘the word’ to the especially interested buyers.  Nowadays, particularly in Internet auction context, the deep pockets crowd present a wild card. Such particularly significant when these folks presented in the numbers observable bidding today. Such diversity, results as expressed in attained prices!  A particular point being, the actual “value” of a gun (or widget) today, much dependent on the scope of ‘audience’ reach, determined by the sale “forum”. Beyond personal direct marketing, such most commonly expressed as, shops, shows, and Internet.

For decades, as these first several, more with nuanced price achieved ‘flavors’.  Now with Internet as gorilla in the parlor, a whole new ball game.  Definitely “market-influential” to say the least. Still, the phenomena of “real world” pricing as many instances ‘yet separate’.  Internet prices to be “considered” in pricing evaluations particularly in context of rare, unusual, exotic guns (pick your descriptor)!  But to my opinion – and others will disagree – we have something of a dual valuation structure.  Internet pricing as “wildcard” but almost assuredly greater than “other” and those sort of ‘tidal influences’, with their definite pricing effect overall. 

In Winchester land, the gathering of eagles here presenting expertise about the best resulting evaluations to be had… Within ‘reason’.  Wild weather Internet auctions “attained prices”, moving to ‘crystal balls’; IFR flight rules without reliable instruments! 

All this dialog on my part, boiling down to original postulations.  Value guides become unreliable/incomplete concerning rare guns with multiple value vectors.  Your request here for instance, postulating. pre 64 + Super Grade + less common chambering + approaching 100% ‘as new’ + ‘ruffles & flourishes’ accessories (boxing & literature)!  Your approach, coming to this sort of Forum, as best possible resource! Congratulations & good luck!  

Here, just my take.

Best & Stay Safe!

John

Hi Todd-

Hard to answer without reference or link to photos of a specific gun. Clarence’s caveats are surely relevant b/c, in certain time frames, potentially undetecable “upgrades” are possible, and when it comes to “rare” chamberings are likely.

In general .250-3000 SAV M70s are hard to fake (MUCH harder than 300 SAV) b/c of the unique magazine box, extractor collar/bolt stop, ejector.  These parts (if correct) were common only to the 250-3000 SAV and 35 REM chamberings, so original parts are in short supply.  An example of a probably good 250-3000 SAV SG is the one Justin’s got:

https://pre64win.com/collections/rifles/products/250-3000-savage-super-grade-rifle-1950

This would be a very late one, given that the 250-3000 SAV chambering in Std/SG was dropped circa 1949.  But I have “barrel clean up” magazine ads as late as 1954 where the factory was trying to dump unpopular chamberings made up from parts they still had in inventory.  I kid you not that you could buy a .250-3000 SAV from Hudson’s Sporting Goods as late as 1954:

As said, Clarence’s warning should be taken to heart.  Before 1954, the ONLY differences btw a M70 Standard and SG were the stock, floor plate, and front sight.  Anybody who says there were unique markings on the barrel and/or receiver in that time frame is simply mistaken.  So if you’ve got the right parts, they’re not hard to fake…

Value of a legit .250-3000 SAV SG in the current market is probably about $10K+.  I can’t recall what I paid for mine (a pre-war piece) many years ago but it was up there somewhere…

As Always Caveat Emptor…

Lou