Carvin Nomad mods

[Smokebreak3]

I had the 212 configuration (Belaire) of this amp in for repair and was really impressed with it. I saw it had been modded and lo and behold there's a whole set of mods for it online from decades ago.
So I found a local 112 version (Nomad) and did my own thing to it. My version which I believe is early with the V12 speaker, has a very robust and easily modded PCB.

The only ones I did from that online set of mods was basically snipping out the clipping diodes on the dirt channel, as it sounds horrible stock. Clean side is pretty damn good stock.
After messing with the TSC, I came to some values for the clean James tonestack that mimic'd a BF scoop, and also for the dirty side that mimics a MArshall tone stack when the treb and bass are turned up, and a tweed type mid forward thing when down. I also knocked down the Rp here and there to 100K, and further knocked the gain down with a Marshall style voltage divider.

My goal here is a great clean side, and for the dirt side nothing much more than a "blues" level of gain. Say early ZZ Top style. I've got it pretty close! The dirt side is very tweedy, but anything above 5 on the Drive knob is still too much, so I'm thinking about a 220k/220k Fender style divider after that gain stage before the PI.
Also, this amp is incredibly loud for a 4xel84 amp.

Speaking of the PI, what is going with the tail?? I drew the presence control in (it's on a diff page), that I will mod for both channels(stock only works on clean).
But can someone explain that? I'd like to simplify this and just make it a 5f6a PI. I would love to hear some thoughts on that, and also any other musings about gain structure or driving/recovering a James tone stack, or other James tone stack values that would work here. Also I'm gonna change the presence cap to .1

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