forged is always better it has more detonation resistance.
nitrous is a little closer to naturally aspirated becuase the extra oxygen and fuel are generally just sucked into the motor throught the throttle body. a higher compression ratio will help not hurt with nitrous
you might want to replace all of the other mounting bolts with new stuff so an old crusty bolt doesn't break off while your tightening it down. intake manifold bolts are prone to this.
you can also save a little money by purchasing a full gasket set it has all the gaskets in it you need