Cool. I'm after something horn-like and was about to build a brassmaster. Then I remembered this and that I got one of your PCBs from the pif box so I'm gonna give it a go
I didn't look very closely but it looks like the synchrowah uses 9mm pots? Maybe you need to use the kind that have a shaft that's knurled and has an indicator like this
https://smallbear-electronics.mybigcommerce.com/9mm-pc-mount-panel-trimmer-tall-shaft-pot/
Tuner, digitech stuff, looper, Gen loss mkii that's about to come off, and I had a deco for a long time that I took off but didn't bother to list for sale
If you mount the jacks closer to the face of the pedal and use low profile electrolytics, the board can usually go "on top" of them. Here's a thread of my 1590a builds where you can see some examples, including an fv-1 with stacked boards