Re: Just bought a 65 super reverb!
Since it has a two prong cord on it, try and run it in stereo with another amp. It may run quieter in stereo than having two amps with a ground. Also, with a grounded pedalboard. Just a thought. Other than that, it probably would be better to have a 3 prong plug on it.
I think if it were mine, I'd leave the pre's, unless I found some of my stash to sound better.
My first move would be to get some TAD 6L6's for lowest headroom or something like Tungsol or Svetlana 6L6's for more body. 32mA is a nice healthy bias.
I tend to not want to start changing components, unless the sound is a bit lifeless even with new tubes. At least you're starting with THE 1965 stock amp. If it sounds great with new tubes, leave it. Scott is right about inspecting the filter caps, just to see it they look fine.
With a pristine amp like yours, it could have gone a long time without powering up, and also left in a cold garage. Extremely scratchy pots and oxidation is the main indicator of this. Also, a weathered looking tube chart sticker.
Or, it was completely pampered by a mindful guitar player who fired it up semi regularly over it's life, keeping all the components full of life. Also kept indoors, where it's components only saw room temperature. Good tolex, pots, and a clean interior are the indicators. In that case, the stock amp may still be perfectly healthy. Start with power tubes.