@Rcurl: I'm thinking it might be difficult to properly illuminate the internal structure of the tubes with LEDs.
I have a cunning plan; indeed, a plan so cunning we could pin a tail on it and call it a weasle -- let me play with my class etching on the regular bulbs this evening (I'm not touching thise vacuum tubes until I'm 100% sure what I'm doing) and get back with you... watch this space...
I think some of those tubes may be mercury rectifiers. If they are, we've got to come up with a high voltage source so you can get a nice blue-green glow out of them. We don't want too much current, though, because we don't want to generate too much ultraviolet light - or even worse- X-rays.
As for the light bulbs- I have heard that some bulbs will act like a plasma globe when energized with high frequency, high voltage AC.
I'm thinking it might be difficult to properly illuminate the internal structure of the tubes with LEDs. Have you considered small lasers, as used in laser pointers? They're easily available and pretty cheap.
So I want to get the light from tri-colored LEDs shining into these tubes without damaging the integrity of the tube -- I have what I think is a really cunning idea -- but before I talk about thst, I'd love to hear other suggestions ... got any?