The GE 12AT7 and Sylvania 12AX7 are both rated for 300 volts (plate voltage) but yeah I've heard you can punish the 12AT7's fairly brutally and they keep coming back. The original AA864 schematic shows 220 and 205 plate voltages on the PI halves, which is typical, like 200V on the V-4 etc.. I tried a few different PI tubes since I've gotten my Bassman back up and running in the last year and I think the biggest difference for me was having a "matched" tube, that's to say both sides that are being used as the phase inverter have very close gain characteristics. I thought it was BS magic from the tube depot till I tried it.
Back to smaller tube amps that cost wayyy too much money, I looked at some Deluxe Reverbs yesterday, and about puked. I may just buy one of those '68 custom reissue joints and put a turret board in it myself, and maybe get some classictone transformers.
Then there is also this:
http://www.ebay.com/itm/ampeg-gemini-2- ... SwPK1ZUFYnIt's pretty rough, but I like the 15.. Ampeg also used some weird tubes in these amps, but I believe you can just change the socket wiring and a couple resistors to use more conventional tubes.. It's just money.