427 FE and TKO 600 mating Question

[elmariachi]

Can't get the tranmission shaft far enough up into the engine to bolt them together:

- Freshly rebuilt Original engine and forged crank
- Lakewood 15210 FE bellhousing
- TKO 600 with short shaft and short retainer
- New pilot bushing
- Lakewood is 100% dialed in to within .005" and bolted down
- McLeod clutch, pressure plate and throwout bearing properly installed with Ford clutch arm.

Pilot bushing was test fit on input shaft. Bellhousing was test fit to tranny on bench. We have the old TKO long shaft as the alignment tool and we can get it to slide in smoothly and bottom out. When we run it all the way in and then measure the perpendicular at the face of the bellhousing mating surface, its 6.5" on the dot. When we square up the tip of our installed short shaft vs. the mounting face on the tranny, its 6.5" on the dot as well. However, when we slide them together, it bottoms out with 1/8"-1/4" to go. We put some marker paint on the tip and confirmed we are all the way into the clutch and pilot bushing.

Thoughts/advice/input?

Thanks.