you know that i have built several amps and lately i am studying and building projects of H. Dumble (which he left us recently). I am very intrigued by his customizations of Fender amps. The models of this factory have always been the starting point for its various models but it has also customized amplifiers for selected customers, the chassis was completely emptied. He kept the transformers and "customized" the motherboards. In industry magazines you will find several tone stack modification schemes that transform the amplifier. I think it would be an interesting development for motherboards dedicated to Fender amps.
I enclose two examples, but there are others dedicated to Twin Reverb and Super Reverb.