If your m/c goes phut, the pedal will go to the floor and stay there. The springs have an 'over centre' action to help push the pedal down. Makes a big difference to the effort required. The newer pedal and box is often fitted to older Defenders.
Hang on! This is the Disco forum! I don't know whether the arrangement is the same on a Disco, though it seems as if it is.
Oh, and you don't need to change the clutch fork on a V8, it's made of cast iron and will never break like the tdi one.