Exactly - the "equivalent" tubes are bound to be off by a little bit compared to the original tube. The Russian tubes might be 6DJ8 equivalent, pin outs etc, but they will most likely chart differently. So you just have to do your due diligence in  documenting what a known good Russian/Chinese version of your tube looks like.  And these are analog devices, made with glass, metal, and some chemical coatings; so there is going to be a wide window that these tubes will work and measure in.

When you find a favorite, document it so when you buy replacements you can filter for the specs of tube you want (assuming you buy bulk and are weeding them yourself).

As for vintage tube testers, there are several articles you can find online to guide you, but the cliffs notes:  they are analog devices that have probably have some drifting in their components as they age, and even if it works, it might be measuring way off. Add to that, even if you refurbished one (replacing all the old caps and resistors that have drifted with age) it would still need to be calibrated so when you measure a 6DJ8 the unit will actually measure in the correct range. Finally, most tube testers only test at the bare minimum voltage, and not actual in use amplifier voltages. So where your amp might be sending 440v to the power tubes, your tester is only running 220v and checking to make sure no shorts or lack of emissions. So basically a tube tester is saying "is it on? and is it emitting within the range I expect (at 220v or whatever that particular tester runs at)".

So a vintage tester can only really tell you a tube works - don't trust eBay sellers that say they were matched on some vintage military tester. Unless their tester runs at actual amp voltage and it putting out full test charts, you really are only ballparking your "matching".  That's where modern tube testers like the Maximatcher shines.  IMHO, if you have a crapload of tubes in your stash, and/or you want to verify you're getting what a seller says your getting, then spend the $1800 for both the modern Power and Preamp testers.

Yes!  The screen itself was built on an oak frame painted black, I designed and assembled myself, with two layers of 4-way stretch spandex (white over black). I basically built a screen for about $250, that would have cost me roughly $2000 if it was a store bought aluminum frame jobby.

I tore it all down, smashed up the frame and bagged the spandex when I had to repaint my old livingroom at the Bolingbrook house, just before moving out. So I have the spandex in a vacuum packed bag to keep it clean, and I'm designing a new frame for the current living room. Right now I'm using Jill's TV in the living room, and I just painted a wall white in the dining room to run the projector on till I get the home theater completely rebuilt. It will probably be a very long project with all the wires I need to run and frame that needs to be built. Including the rewiring and installation of all the smart lights. I'm even considering smart shades in this new setup.