Power is 50V-0-50V 150mA to give over 62V raw DC, plus a 6VAC which may not be used. One version had higher taps to light a neon with AC; today an LED off the DC would be a better idea.
Actual current draw is probably under 70mA at full roar, 30mA idle. With modern (do we dare?) bridge rectifier and regulators, a 36VAC 100mA PT should be ample.
Input is 600:600 with primary options for that 150-ohm radio network. Since the whole box is nominally unity gain, the input must handle the same levels as the output, 1 Watt max 0.25 Watt with low THD at 20Hz.
I am not happy about the documented OT primary connection; it gives 25 ohm load on the amp, the amp has 100uFd output cap, is unlikely to drive 25 ohms to 20Hz.
Check: unit is rated for +30dBm output, 24.5V RMS or 69V peak-to-peak into 600 ohms. Amp is powered with 33V DC, is good but not great, can swing 25V-30V peak-to-peak. Assuming OT ratio is no higher than required to satisfy a +30dBm spec, OT ratio must be near 1:2.3 to 1:2.8 turns ratio. Primary impedance must be 76 to 113 ohms.
Since we are not driving transmitter or recorder-bus lines, and the original is BIG and should be uncolored at "normal" operating levels, the exact value is not critical. 150:600 would smack the snot out of any modern load, maybe smoke it. Some increase of gain will compensate the ratio difference to get unity gain in bypass.
To preserve transparency, OT should be sized for 1 Watt at 20Hz working far below saturation so we get 0.25W at 20Hz with under 1/2% THD (and smaller for more bass-tone color).