I have not worked with the Fender, but the Peavey does not react all that much to tube choice. I think you could swap the EL84s with some JJs or EIs and have a slightly cleaner, tighter sound, but it will not be fundamentally different. Bob at Eurotubes can pick out a hot set of EL84s that will make the amp go into power tube overdrive a little bit faster, but you are talking about having the amp turned up very loud to hear it.
As for preamp tubes, you should consider an NOS tube for V1 (12AX7 or 5751, but I would shy away from a 12AU7 or 12AT7), like an RCA or a Philips, or possibly an Electro Harmonix, a European tube for V2 (JJ, EI, or Mullard or Brimar if you are feeling crazy), and a high gain, low noise Chinese or Electro Harmonix tube for V3.
www.kcanostubes.com is a good resource for these kinds of preamp tubes.
If you are fundamentally unhappy with the Classic 50 tone, sell it or trade it toward something else. You are not going to get it to sound different without drastic modification, and there are people out there who like them stock. Steve Ahola has such mods on the web, but you are looking at a virtual rebuild of the circuit.
Good luck
As for preamp tubes, you should consider an NOS tube for V1 (12AX7 or 5751, but I would shy away from a 12AU7 or 12AT7), like an RCA or a Philips, or possibly an Electro Harmonix, a European tube for V2 (JJ, EI, or Mullard or Brimar if you are feeling crazy), and a high gain, low noise Chinese or Electro Harmonix tube for V3.
www.kcanostubes.com is a good resource for these kinds of preamp tubes.
If you are fundamentally unhappy with the Classic 50 tone, sell it or trade it toward something else. You are not going to get it to sound different without drastic modification, and there are people out there who like them stock. Steve Ahola has such mods on the web, but you are looking at a virtual rebuild of the circuit.
Good luck