this is all considering that the noise is indeed coming from the bellhousing, if it's inside the transmission it's a whole different story:
- bad pilot bearing
- ask him if he clocked the flywheel properly (unlikely but seems that some people do that, not sure how though)
- the other thing i can think of is the inspection cover withouth some of the bolts
by the way he describes it i would think to be more of a driveshaft issue though.