The first coupling cap is WAY too big, something like
.47 where it sounds best with a .022. I would imagine
the thinking was that the .47 would garner some more
bass response from the funky cab design and 8 inch
speaker. I changed the two preamp tubes to a standard
fender arrangement with a 1.5k cathode resistor and
100k plate resistor. I then tweaked values of the input
resistors to the second stage to get the sound where I
liked it. I have experimented pretty heavily with the
tone circuit, and ended up leaving it pretty much stock. 
 
The power amp...
 
This is where most of the other faults lie in the amp.
The power supply puts out something like 430 volts
stock. This is really very high for a true SE class A
design. I installed a 25w 600 ohm resistor (could of just
used a 5Y3) to get the plate voltage down to around
320 volts. I then installed a 1.5k grid resistor and a
220k ohm resistor to ground on the input of the output
tube and bypassed the 470 ohm cathode resistor with a
1 k ohm resistor to get around 320 ohms cathode
resistance. I installed a large (150 microfarad) bypass
cap across the cathode resistor.
 
The amp now sounds MUCH better. I recently built
one of these for my brother and installed the amp in a
2x10 cab with a couple of old CTS speakers I had
laying around. I was really suprised how good it could
sound, even with the poor stock iron.
 
As the previous post said, it's a great experimentation
platform, just make sure you DE-solder all the joints, as
the traces peel up way too easily.