Major Clutch Problems

The car is a 93 mustang with a T-5 and a 302.
I am having difficulty re-installing the transmission, the flywheel has been resurfaced, installed a new Ford Racing clutch, used an old input shaft to line clutch disc with pilot bearing, new pilot bearing. Dummy shaft slides in and out fine. Installed bellhousing. Now the fun. Placed the transmission on a tranny jack, put it in first gear to spin the output shaft till it lined up with the clutch disc spline and tried to slide the tranny in. Goes in a couple of inches and stops, wiggle push, manipulate angle of motor/tranny relationship but the tranny will not go in, still close to a 3 inch gap between tranny and flywheel.
I have replaced the clutch twice before without any hick-ups. Once with a King Corbra Clutch and once using a LUK.
Anyone else experience similar problems with a Ford H.D.?
Have I missed something?
Advice suggestions welcome, getting frustrated need the car back together this weekend to get to work on Monday.
Thanks

Clutch

Thanks for the responses

The input shaft and 'dummy' shaft used are identical and are the correct match for the car. (10 spline etc etc.)

The pilot bearing has been replaced, twice actually since it was the first suspected culprit. The dummy shaft goes in no problem, which is the boggling part of the ordeal.

Reef Blue