Here's the Klon again. I wanted one with board mounted pots and for a smaller enclosure. You might be able to fit this in a 1590B with low profile jacks, but it will easily fit in a 125B. It's designed for 9mm PCB mount pots, though it might be difficult to find the dual-gang Gain pot. Look for Alpha part number RD902F-40-00. I've removed a few components that were apart of the stock bypass switching for the sake of space, so you'll want to use your true bypass method of choice with this one.
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.