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

Working with my pal Brian to install his HEMI four speed through a dual disc Mcleod assy in a Quick time bell housing. I've done lots of four speed installs but never had one fight like this. Always single discs though. Can't seem to push it in no matter how many times he lines the discs. It literally feels Locke don the shaft but it all fits fine out of the bell housing. It has a new pilot bushing and the trans goes in it fine. If we get close and use the clutch pedal for the last half inch or so, the back disc drops slightly and then it all has to come back apart.
What are we missing with this? The SOB is heavy and tough to deal with.
Thanks!
Tom