470µF, 35V - replaced with 560µf, 50V - not a problem, (except why?) providing you did each channel the same.
It is possible the silk screen on the board is wrong. Measure the voltage on the + side and - side of each cap. Make sure the polarity of the cap matches the voltage and the voltage does not exceed the rating of the cap. Then put your meter on AC Volts and measure the voltage across the cap. It better be 0V. If not, you have a blown rectifier putting AC across the cap.
Well, now you know why you're killing the negative rail caps.
I'd do a full swap of every semiconductor on that +/-33V regulator, and a careful test of the associated resistors. And the caps at the output of that reg need to be removed and thrown away.
The preamp boards all have input filtering caps on them as well, and these need to be swapped out.
The ceramics (C14 & C15) are probably rated for at least 100V, and are non-polar, so I'd doubt if there was a problem with them.
Note that all the preamp boards have some sort of local filter where the +/-33V comes into the board. I'd make the assumption that these parts are no longer viable.
As far as a fix, yes, I'd clean house and change out every semiconductor in that 33V regulator. Your 1N4148's are likely OK, but give 'em a diode test and confirm that they are installed properly.
The type of ceramic cap is not terribly important, but there's a Kemet ceramic that looks to be pretty small and rated for 500V: #80-C322C473KCR.
As far as the replacement semi's:
TR01 -> KSA1013YBU or KSA992
TR02 -> KSC2383YTA or KSC1845
TR03, TR07 -> KSC945CYTA (center-collector, hence the 'C' suffix)
TR04, TR08 -> KSA733CYTA (ditto)
TR05 -> MJE15032G
TR06 -> MJE15033G
ZD01 -> 1N5234B (#512-1N5234BTR)
I'm also concerned about your values for R05 and R06. From your pics, they look like 100 ohms...is that right? Scat calls for 330 ohm at R05 and 270 ohm at R06, but IIRC it seems that both resistors were 330 ohm 3W. Bottom line is that with a 70+V input voltage and 33V output, we need to drop some of that before it hits the pass transistor to help keep it from burning up. 100 ohms, if that's what is in there, is way too small.