I believe the originals run off a 9v supply, but newer ones have a voltage doubler internally to run off 18v. Since I know there are different preferences when it comes to those, so I left it off the board. I realized after I drew all this up I probably should have included trimmers for biasing the JFETs, so you may want to socket the resistors going from voltage to the drain of Q1, Q3, and Q4-6. Though if you're using in-spec J201s (I highly suggest the SMD version and conversion boards) the stock values will probably work fine. YMMV Pots are board mounted and will fit nicely in a 125B.
This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.