The most common procedure for balancing a diaphragm spring pressure plate is to weld a short piece of round stock to the cover, sort of like a wheel weight. The Borg & Beck style pressure plate has a series of holes drilled in the cover, and a slug of Mallory metal (heavier than lead) is tapped into one of more of the holes for balancing purposes. Spinning the flywheel and clutch cover is a good idea- - -including the disc isn't, because there's no way to predict where it will lock up when the clutch is engaged because it's splined to the transmission input shaft.
Jerry
