Pick a pair of pressure plate bolt holes and measure the distance between them (center to center). If the flywheel was drilled for the 9.5” diameter pressure plate the holes will be exactly 3.00” apart. If it’s been drilled for a 10” pressure plate the holes will be 3.125” apart.
If you’re running a transmission with the big 1-3/8” input shaft, you should not use the 9-1/2” clutch setup as the fingers of the pressure plate are too close together and can hit the front bearing retainer of the transmission (as well as the release bearing carrier hub).