Does the clutch work with the cable adjusted so the pedal is up against the underside of the dash?
First thought is thats where the pedal should be, all the way up.
You want it lower? Sometimes you don't get what you want.
Second thought is, the cable is installed in such a way that cable movement is required to take up slack in the system before the clutch starts to disengage. IE: I don't know how the fork is kept in place over the pivot, spring fingers, spring clip, if the retainer get between the pivot and fork, that could cause problems. 2A: Or the throw out bearing retainer clip could have gotten on the wrong side of the fork. 2B: Or the cable housing could be flexing.
I've had both factory V8 and V6 4 gears, the V8 when new. The difference was night and day, the V8 had a medium light pedal feel and could be adjusted in te upper ~ 1/4 of travel, the V6 ... every time I disengage the clutch I was expecting the cable to snap or something somewhere to give, it was that heavy.
