Well if I had your killer amp, I would find a way to buy a quad of matched Mullard power tubes. Then a Telefunken in V1 and a Raytheon Black Plate in V2 and a Sylvania in V3.
I have the preamp tubes and I will have some RFT NOS power tube in about 2 weeks. The RFT's are pretty close to the Mullards in tone.