Sorry for the delay. I got held up at work, then came home, inspected, and found that I had two unsoldered resistors (a 75K ohm between 14L and 15L, and a 75K ohm between 18L and 19L) near the tube sockets that were causing the excess heat in the power section.
So, I got it working, and the bass response was a little underwhelming, so I moved on to the Integration upgrade. I got the shunt regulator installed, it was working, and I hooked it up to listen to while I worked on the two C4S boards. I played probably 10 songs through it, and it suddenly started making a noise that sounded like when the needle skips across a record. I unplugged and soldered in my C4S boards, thinking I'd rather troublshoot the whole thing at once, and now only like half of the LEDs light (3/4 on the shunt regulator, 2/4 on one C4S board, none on the other, and 3/4 in the tube sockets).
I also am only getting ~50 volts at terminals 2, 1 8, 26, and 31, rather than the 65-90 volts DC specified in the end of the Integration manual.
My question now is - could those resistors have burned out and caused the sound I heard after playing a few songs with the shunt regulator installed?
Pics have been uploaded of the tube sockets, the other side of the power section, the LEDs that are and aren't lit, and an overall pic of the assembled unit.