Thank you to everyone in this thread for the help!
The plate voltage is 485.6 (8 to pin 3).
Bias before: (8 to ground) 13.609, 14.307, 14.268, 13.620, 6-7 watts! No idea why previous owner had it so low.
Bias now: 36 mA on all four tubes, about 17.5 watts, and what I think is about 70% of...