[Jim Sims]

Depends on it's state; does it have thermal reactors? Does it have any pulled head studs?
Most normal engine rebuild procedures apply: inspect and measure everything and repair or replace if damaged or out of tolerance. If your emissions inspection rules permit, the thermal reactors should come off and be replaced with three to ones or even better with SSI's or early style heater boxes but this addition will require removal of the lower air injection and EGR systems.
Valve guides should be replaced with the better silicon bronze type. If a head job is being done, have the machine shop change out the "necked down" exhaust studs (head to to thermal reactor or heater box joints). Pressure fed chain tensioners should be added. If there are pulled head studs or you're pulling the case apart then significant checking and machine work will likely be indicated. The case will likely need to be squared, bored and thread inserts (case savers) added (don't forget the 8 mm stud inside). New Dilivar studs.

Other helpful upgrades: 5 to 11 blade fan, external oil cooler, modifications to cylinder baffle sheet metal.