Trouble Installing 18 spline A-833 through dual disc clutch assy.

Comes with plastic one but my concern is there are three items that have to be exact. if the plastic one is even remotely down or up or sideways, it still lines up but the tighter fitting splines of the input shaft will not push through them and the pilot bushing.
With the trans not in the way, you cannot push on the clutch pedal to let the throwout bearing help align it all with the plastic one in as the throwout bearing pushes sideways on it and then misaligns the two discs.