Not looking to be a buzzkill, BUT:
I have entertained that idea a few times, but always realized (I love that term when it comes to pedalboard-related shenanigans) it's not worth the hassle.
Power requirements are all over the place with the old aluminium "Trapezoid" EHX stuff (center positive, 9V, 12V, 24V, wall warts, internal PSU, etc).
And they get wacky, if they aren't already. PCB's wobble as you turn a knob, footswitches become unreliable, toggles and faders break, enclosures catch rust, battery doors get in the way (looking at you, NYC BMP and Octave Multiplexer), yadda yadda yadda...
Maybe some day, but I gotta have my priorities set, I guess.
You'll certainly need lots of elbow grease and occasional TLC to run an all-vintage-EHX spaceship.