76 duster clutch pedal will come up 2-3 inches off the ground but not all the way

Yes you have to make a shim to place between the fork pivot and bell housing to get the proper throw on the clutch fork. I made a 1/4 inch shim for my 66 Dart with a Long adjustable pressure plate. With the diaphragm clutch you may need a thicker or maybe thinner shim for your year and set up.