Same way you do when reassemble any engine... Slide the pulley on, check your eccentric shaft depth, and bolt it home. Yes, usually, the engine the engine is vertical during a rebuild, but its not required.

Since you're not pulling the front pulley forward, why would the stack come apart and let the bearing drop?

 

Or the oil that is coating the bearings already makes the parts stick together....

But you're welcome to try your bazooka joe.

 

Do you recommend i leave the comic strip with it? Lol

 

Gasket material!