hello all. This is my first post,  and I am new to the inner workings of tube amps, but I have already learned alot just by reading the posts here .
I am working on ordering a 1986 bass plexi. I've been discussing several mods with Nik that I want him to build into the amp and I wanted to hear what you all think of them:

1) Add a .68ufcap on V2 cathode ala plexi (lead) and wire it to a push-pull bright vol. pot to take it in and out of the circuit.

2) Add a .68uf/2k7 to V1 cathode and make this also switchable via a push/pull normal vol. pot. My question here is how will this sound, being it is shared cathode? Maybe It would be a good idea to put a switch on the back for shared/splite cathode?

3) Push Pull bass pot to defeat the tone stack. I read about this mod being done on 18/36 watters, but Has any one done this mod in a plexi? What would this effect the tone, gain etc.?

4) Negative feedback switch to turn NFB on/off , and a 27k NFB resister with a 5ok pot on back panel to adjust NFB. Again I've heard of doing this mod to 18/36 watters, but not sure what to expect with a plexi. Has anyone done this one?

5)Ext bias mod + switchable bias resisters so i can switch from el34, 6l6 and 6550 tubes with only a bias pot adjustment.

If anyone has any comments or suggestions on these mods I would love to hear them.

Thanks!