|If you're re-sealing your exhaust valve covers, those would be a prudent move. You'll never need to replace them.
If you haven't already, do your coolant line bypass as well.
Additionally, you should replace your PCV's and PCV hoses if you're not sure when those were last done.
I think the next time I pull my plenum I'll look into switching from bolts to studs/nuts for the upper plenum. Sole reason being it would make re-aligning the upper plenum easier since the gasket can sometimes shift when re-installing the upper plenum. But that's totally not a must-have thing to do.