Unless you propose a circuit the flat out won;t function, do whatever you like. But know this: tube engineering was a mature industry 75 years ago, guitar amps have been around as long. There really is nothing you can come up with for these amps that has not already been done. Not saying don;t try stuff, please do and have fun.
Separate cathode resistors on the power tubes? Been done, go ahead. What benefit are you hoping for? That is the standard question. What do you want it to do differently?
You have a common cathode circuit on the input, you could make them separate like a zillion other fenders. You can try eliminating cathode bypass caps here or there. You could go to one input channel and parallel the two input triodes on it. Nothing that I can think of either that will not already have been done. Look at the body of work in the Fender file, all the variations on power tubes, on phase inverters, on tremolos, tone stacks, etc.