Pyramid PS-21K voltage mod

[KA2PTE]

Recently fixed one of these up, it had a bad bridge diode block. I went and installed
an LED voltage display readout and its operating well, delivering nearly 25A.

I need a supply that will deliver 26V at a low current no more than 100mA,
and also 50V at about 2A max and was curious if a voltage doubler of some sort
could be put in as a mod to double the 13.8v once for the 26V, then again for the 50V
perhaps a quadrupler? Is there a fw quadrupler circuit comewhere?

The PS right now uses half the diode bridge block as a FW center tapped setup, and I wound up ditching that
for 2 stud mount high current diodes that were in my parts bin...in the photo.

I am thinking maybe a DPDT center off switch of some sort to bring the dual doublers in and out perhaps.
The 2N3055 transistors are about 60V rated, so they should handle the higher voltage, and perhaps
I will have to upgrade some of the caps...and maybe the op amp board would also need some changes?

I could maybe put in a zener or something to keep the op amps voltage B+ clamped during the
voltage changes....the voltage adjust pot VR2 I suppose I could calculate and switch in 2 different
trimmers to allow precise trim to 26 from the 27.6 doubled and the 55.2 doubled once again.

Seems to boil down to the type of quadrupler and perhaps the ground setup?

I placed a FW bridge on the 2 outer wires of the primary of the xfmr and with a filter cap
I have about 49V DC. so its probably a 40 or so volt center tapped xfmr.