business property auction tomorrow, hock roadsters?

["DAVID J. PEAY" <djp4@sbcglobal.net>]

I HAVE A 1968, SPL311, 1600, WITH 300 MILES ON A COMPLETELY REBUILT ENGINE. I 
INSTALLED SPLITFIRE SPARK PLUGS #SF6D WHICH CURED THE ROUGH IDLE AND MOST OF 
THE MISFIRING..
  PROBLEM: ENGINE HAS A SEVERE SPARK KNOCK UNDER LOAD AND ALSO MISFIRES IN 3RD 
& 4TH UNDER LOAD.  IT RUNS OUT WELL THROUGH 1ST & 2ND GEAR UP TO 4000 RPM AND 
THEN A POSSIBLE MISFIRE--- SOMETIMES.
  CAN ANYONE ASSIST ME IN CORRECTING THIS PROBLEM??
  THANKS;  DAVE (INDYDATSUN)
  ANY ROADSTER LOVERS AROUND INDIANAPOLIS??