The PCB is original; it's the tremolo circuitry and recovery stage for the reverb! The only caps that appear to be non-original are the two, blue Xicon electrolytic caps for the negative bias supply. Replacement of the original can capacitor is problematic in that higher wall voltages of today will cause the DC delivered by the transformer to exceed the voltage capacity of the replacement can capacitor. Your amp tech should understand this. You can search this forum for work-arounds to solve this problem. With limited space under the chassis, I would consider a pair of capacitors wired in series (totem configuration with 220K 2 watt balancing resistors) in front of a new can capacitor for the later stages.
Good Luck!