Well, I picked up a 1995 Trek 820 today. It's the first MTB I've found that is my size and in fact, I'm not sure if it's the size I was looking for or the biggest size they made! I'll measure it as soon as I get it home but eyeballing the standover it looked fine. It's got Cro-mo main tubes and a cro-mo fork with hi-ten stays. Components are lower level Acera X, mainly. I downloaded the 1995 technical manual and the 800 & 820 are the least aggressive MTB's made that year, with the 830 having a more forward, leaned over position. This is something I didn't know and a good thing since I'm using this as a test bed for a future custom frameset that will be fairly upright in rider position. The bike is in surprisingly good shape and it shifts well. I forgot to check the brakes (easily fixed...even by me) and of course, both tires are flat. It also has a stem extender so the bars are WAY up there and this is the second 1995 Trek I've bought that had a rack on the back (the first being a 730).
EDIT: It turned out to be a 22.5" frame, rather than the 21" frame I was wanting. Surprisingly, standover isn't a huge problem (84cm). It's a bit uncomfortable but workable for a test bike.
I got the fit roughly dialed in and have been taking it for quick rides around the neighborhood. The knobby tires are driving me nuts and I don't see how anyone can ride that type of tire on pavement. Once I get some Big Apples on it I'll reevaluate but even with the knobbies, I like the ride. I do a lot of 90 degree turns in relatively confined spaces and 26" wheels have a lot higher confidence factor than 700c wheels. Makes sense given the smaller diameter of the 26" wheels.
I can't imagine what a relatively light weight, sporty geometry, 26" wheeled bike (compared to this very heavy, stable MTB geometry 26" wheel bike) will feel like but that is likely the direction I'm going with my custom.