The Amp Garage

are PEC pots similar to the ones being sold under Alessandro amps brand?

Yes. Alessandro pots are PEC's.

However, it is entirely possible that there is some inductance from that resistor that helps shape the tone. It physically can't. Wirewounds such as the ones used on Wrecks show very little inductance and have totally negligible effect in a power supply RC network. According to "legend," EVERYTHING...

any thoughts on this?

The actual values aren't critical. You may use slightly different value R's, 2w or preferably 3w-rated.

Also I'm haven't been able to get the 25w 1k resistor, would a 17W workout?

It will. the original 25w is vastly oversized : a 3 or 5w model is more than adequate!

Question what were ken's favorite preamp tubes for a express.

Either selected Tungsram or Telefunken flat plates ECC83's. Power tubes were RFT-manufactured Siemens-branded EL34's.