Dang Ckau, I didn't know you were building this little gem. I may need to make it a little further west and see this one in person.
I made my brakes adjustable via threaded rods on the pedal to (Carter) master cylinder, but I have to stop and use a wrench. I'm interested to see if the prop valve will function as you intend it to. We used two prop valves on some of our pavement cars, one front to back and one left to right front. As you said , helps turn the car on corner entry. Until they outlawed the side to side adjustability.
Looking good so far man.