gm clutch questions

Hey guys, I am new to this site but have been wrenchin and wheelin for a long time now.   I just built another toy.  A 1965 gmc on a 1975 3/4 ton chassis.  i built and installed a 427 with a sm465/np205 combo going to a dana 60 and 14 bolt (both locked).  my problem lies in the clutch linkage.  I had to modify a bit the original '75 bellcrank to work w/ the pedal linkage of the '65.  So far there is no bind but so much pressure the ball stud on the bellhousing keeps breaking off, and there is not enough freeplay.  I was wondering if anyone has had any luck swapping in a hydraulic bellhousing from a '89 K series.  The 427 has hooker super comp headers on it and the rh header is a b*^$& for clearance.  It is so tight it literally sits on the starters outermost mounting bolt.   any suggestions as i really dont want to waste time and energy pulling out that heavya*& trans&case combo.  Thanks