Rick, I thought you'd already retubed your 275's. Still running those OEM time bombs? The correct term for used vintage tubes is ANOS (almost new old stock) NOS should be reserved for brand new tubes that at most have only been powered up for testing (but nost sellers are just a little sloppy about that.)
OTOH, really unused, but old tubes, can be uncertain performers. They can have developed leaks, or become gassy (which only shows up after they've be run for awhile) or have internal damage (that causes shorts to happen but maybe not right away.) So sometimes (slightly) used is better -- like with used cables that have already had some break-in. Most of the vintage tubes I've bought have been used, but tested new both for transconductance and remaining life, so I'm not concerned about their performance. Let me put it this way: I've had bad tubes test 'good', but never a good tube test 'bad' ;-)
You don't trust eBay thorman? OK, so what's your point? You either take the time to educate yourself, with or without a mentor's help, so you can buy/bid with confidence or resign yourself to paying at least 3 times more (and up) for the same thing from a tube seller. And you stand a better chance of finding what you want faster on eBay.