OK, cool - this is more of a clean-sheet-of-paper design then. It will be fun!
First off, the power transformer. Is it a Hammond 200 series, or 300 series? Reason I ask is, the 200 series is not very tolerant of excess input voltage and you may want to find a way to get that down.
Do you have two power transformers, or are you planning to use one and make a stereo amp?
So, next I dug out the article. Man, 15 years was a long time ago! As it turns out, I have made substantial changes in optimizing the operating voltages and currents. Fifteen years ago, I just worked off the WE table; since then I have derived a model that also predicts the distortion. I now prefer to use just the points with lowest distortion, even though they do not generate the most possible power. So here's today's best approach:
The -204 is a great-sounding transformer but probably the only one of Mike's products that is not conservatively rated for plate current - 60mA is the maximum you'd want to use. By my current rule of thumb that means about 275v plate to cathode, and about 55v bias. The '204 will drop 8 volts (it's 135 ohms DC on the primary) so a B+ of 338 volts is about right.
A 400-0-400v transformer, lightly loaded with a pi filter can easily make 500vDC. That's way too much! But a choke-input filter would be just about dead-nuts on. So that's what will be my recommended starting point.
Personally, I'd stay away from mercury-vapor rectifiers, purely for safety reasons. Back in the day, they even made a tube called the 83-V which was a non-mercury (V for vacuum) version; the "modern" version is called 5V4. There's a certain enthusiasm for the 83 on the TubeDIY forum at AA, but I just don't think it's sensible for us amateurs.
