Hey Anders - here is pretty much the layout I used to make mine. As you can see it is very much based on IVIark's BoR layout . This one is modified to include a bass pot - and it works in an interesting way. At just before noon on the bass pot it sounds exactly like the regular '59 sound, but as you go higher it adds gain and girth and quite changes the character of the pedal. I think the regular version is well designed as regards low end but this takes it into another direction - and it gets very heavy.
I have built this and it works. I hope you don't mind me adding it here - if you do please let me know.