Is it really hard to shim a 10 bolt carrier correctly? Its out of a 94 z28 thanks.

 

Shimming the carrier is easy. You just move shims from side to side 'till the lash is right after you've got the preload right.
Shimming the pinion to get the gear pattern right is the hard part and the reason that I have a pro do my gears.
So if you are just changing the carrier and using the same gears without moving the pinion, go for it.