Clutch fork length

Just went through this with my used Lakewood scattershield. Supposed to use the 12 1/2 fork, they have their own specific pivot, don't think that you can cross those up, the fork won't mate with the throw out sleeve. The 12 1/2 fork pushed in hard, that's with a diaphragm clutch. Found the angle off severely for the adjustment rod, between the fork and z-bar, the fork was binding on the pivot from vertical down load. Put the approx. 11" fork and pivot back in and the adjustment rod was back in alignment, easier pedal push. Also, no over center spring.
So take a good look at the geometry of your stuff and go with what works for you. Take a good look at everything.