I have to replace the intake manifold on my 5.8L 351W in my 1992 F150. (Bolt sheered in the block, drilling it out ended up bad). While I am doing this, what else should I be doing since I have the manifold off. Its a low mile vehicle (75,000).

 

Depends what condition it's in. Some low-mileage engines have been abused or neglected. Some leak. Some have damage. Without more information, we could only guess. Post pics.

 

Intake bolts quite often break off; usually the ones in the corners. Generally you pull the head to fix that - drill it out bigger and install a heli coil. Very common.
If you take the heads off, might as well have the valves cleaned up. And new valve seals installed.