The drawing is incorrect.
To use 4-pole caps in the original Stereomour, you can simply replace the 100uF/450v caps with suitable 4-pole versions. The positive input of each 4-pole cap comes from its 360/1200 ohm resistor, with the positive output going to the appropriate channel (plate choke and C4S board). The negative inputs are tied to each other and to the negative of the doubler; the negative outputs are separately tied to each other and the ground buss.
Leave the voltage doubler, including its two 270uF/250v caps, as is. If you want to replace the doubler caps, that will call for a different circuit. You can't get full 4-pole performance, you'd effectively be using them as 3-pole.