Drag car brake/proportioning question

I ran for several years without a prop valve. I factory disc's up front and wilwoods's in the rear. U always had a bad shimmy from the front under hard braking running 1/4 mile. Someone said that I may have to much braking in the front and it's on the verge of locking them up. Dr. Diff said this may may be a problem and would have to put a adjustable one on the front brakes only, which I already plumed in for this year.

From what the Dodge manual said about my old truck is that the factory prop valve sends fluid to the rear first. Once it reaches xx internal pressure it then sends it to the front. I would imagine that's how they all work.