Post a pic of the "proportioning valve" please.....
Was this a drum / drum truck to begin with? If it was and you are reusing the original distribution block it will be difficult to get a good pedal.....
There is an electrical switch in the distribution block that is used to identify a brake circuit failure....to bleed the system, remove the switch ! it can lock over and cause all sorts of issues....
Are the rear brake shoes adjusted correctly?
