the tune should take care of the timing issue for him, if he goes wet kit, spray after the MAF (tb spacer) if dry, spray before
the reinforced manifold isnt an issue, if youre that worried about it, find a L26 UIM
reinforced intake only survives a BAD mistake. What you should really aim for is to avoid the mistake.
Make sure the fuel system is up to the task, depending on the hit a stock pump might be fine IF it is in good condition, if it is original and 8 years old then it might not be up to the task.
Wet kits do not need injector upgrades and if you upgrade injectors for a dry kit you have to retune for them.
Personally I think an aftermarket ignition box like the Mallory is important for nitrous use. Gives a spark based rev limiter most stock ones are fuel based and would be instant death for the engine on nitrous. They have a window switch so you can shut off the nitrous during the shift saving the tranny, and you can have it pull timing instead of losing NA power due to a low timing nitrous tune.
Going to want to put in colder NON PLATIMUN plugs too. Cheap plugs are fine for nitrous, actually prefered over platinum or iridium.