Monoblock style power supplies, preferably essentially 2 mono amps in one chassis.
Linear power supply. No SWPS. Honest, stiff, linear power supply. It's got to be an arc welder in disguise (and in stereo)...
If it was an original PL 700 amp it would have to have a WO designed backplane and of course it would require a WO light board.
The 700 amp should have all input AC wiring in the same location as the transformer, full wave bridge rectifier and reservoir caps.
It should also have the Lee inspired heat sink for the output stage BJTs.
Squeezing a few more volts out of the rail voltages would be cool. Finding a replacement cap that was 22,000 uF at 125 V or more in the right size would be another good addition.
I am surprised that these 0.22 ohm 3 watt metal oxide resistors in parallel on the positive and negative DC outputs of the 35 amp bridge rectifiers can handle the inrush surge current on start up.
The method I have successfully used for current sharing in very high current power supplies is to use wires of equal length and diameter on each terminal of the bridge rectifiers in parallel. These wires act as very low ohm current sharing resistors with a very high surge current handling capability.