As 2+2GT said the stock linkage will work well, but needs to be gone through from the pedal to the fork. Bushings on Z-Bar, lube, etc. The usual main culprit of hard to push pedal is at the pedal support under the dash. First the plastic bushings wear/crumble and then the shaft wears into the pot metal bushings and as the wear gets more extreme the steel frame wears into the shaft. A roller bearing kit for your pedals is by far one of the best upgrades you can do for your clutch linkage. While the Scott Drake kit is a little easier to install (if you pedal shaft isn't damaged/worn), I personally prefer the Mustang Steve kit. The Scott Drake kit uses the pedal shaft as the inner bearing race, so if the shaft is worn at all it will need to be replaced. The Mustang Steve kit uses a complete bearing with an inner race and will be OK with all but the most severely worn shafts, he will even do the upgrade for a reasonable price if you ship your pedals to him. To check pedal bushing wear, put left foot on the clutch pedal and right foot on the brake pedal, then lightly press the clutch, then the brake and back and forth. If the pedal or pedals chuck/move back and forth/side to side something is worn, the more that it chucks/moves the more severe the wear.
Just My $.02,
Gene