I just saw one of those pop up on Ebay. I have 40s and 50s 274Bs from Western Electric and Sylvania. The mica plates on the top are a dead giveaway that that tube was made by Sylvania. You can see pictures of the Sylvania one like I have in this Japanese auction:
http://yahoo.aleado.com/lot?auctionID=f155796427 That is the same as the Tung Sol pics you posted. The mica on the WE tubes look like this:
http://www.ebay.com/itm/Pair-of-vintage-Western-Electric-274B-with-square-getters-5752-5852-/252040439379?hash=item3aaec7e653. Another issue I see with that tube is that I have never seen WE use an etched side on a 274B, and certainly not a stop sign. The font mismatch on the base for Tung Sol and 274b unnerves me a bit as well. So I cannot say definitively that the ones you sent are not WE made. But, well, they look a lot more like the Sylvania 274B tubes than the WE made 274B tubes. I would not be shocked if that is a rebase of a Sylvania with someone doctoring an old Tung Sol octal socket or, possibly, Tung Sol rebranded a few many years in the past. Regardless, I would not buy it as a WE tube. If you can get it for $150-$250, it would be worth it to compare it to a Sylvania up close as it is also a good sounding tube. Probably my 304th favorite rectifier. But, well, there is a difference in sound between the WE and the Sylvania. At least in my applications.
I will note that the Sylvania 274b tubes were made in the 1940s for the war effort. Most I have seen are 1942-1943, predating most of the WE 274B tubes on the market.