Ground Pour in Power Supply PCB
Ground pour is all fine and good, but don't make the high AC current traces part of the ground pour. 

In particular, the conductor between the large 4700uF filter capacitor and the bridge rectifier should be a separate conductor and not through the ground pour. Similarly run the trace from the regulator +Vin to the capacitor and thence to the bridge. You may wish to put capacitors across the bridge diodes. 

2M2 for the pot? How many volts is this supposed to be? That's about 12kV if I did the math right. You using hydrogen thyratrons?