All we really have here is a standard 1959 Super Lead. And I'll caveat the following with the fact that the image is blurry and I'm just giving it a quick glance.
The gain stages are cascaded. V1a cathode is 2K7/0.68uF or 0.1uF. Probably 0.68uF. V1b is 2K7 and some unknown value bypass cap (the blue electrolytic). V1a coupler appears to be 0.022uF. V1b coupler appears to be the same. V1a plate resistor appears to be 220K. V1b plate is maybe 100K. Each one is bypassed by a small silver mica cap. Probably 100pF. These just tame some highs, reducing the chance of HF oscillation. I can't see a bright cap on the gain pot, but maybe there is one.
V1a coupler feeds the volume (gain) control via a fixed resistor and cap. The resistor is dumping some signal to ground and forming either an RC or divider. Hard to tell from the photo. There is another silver mica to ground forming a low pass. This is fairly pedestrian stuff. Another resistor on the board dumping some more signal to ground. V2 is typical cathode follower and an unbypassed gain stage. Looks like maybe the low input inserts here via a grid stopper. Hard to tell.
Tone stack appears to be 47K and some unknown treble cap value. Probably 470pF or 500pF or whatever, it doesn't really matter. The rest of the circuit is typical 1959 except the PI caps are either 0.68uF or 0.1uF. That cap just before the PI output is typically 0.1uF and the PI caps don't match its size, so they're probably 0.68uF. So the amp is a bit more wooly/woofy compared to a Lead circuit. Sort of between Lead and Bass. That's it.
Ok, $4,000 please.
This mod is one of the most basic, simple "mods" I've ever seen. It's basically a 2203 with some of the highs dumped to ground and slightly more punchy gain stage biasing values in the first two stages. Booooooring.