Wussie,
The only reference I have is my trusty UH-1 gunship walkarounds book by by Wayne Mutza and that is more than sufficient for getting some appreciation of the variety of craft used. There are tons of photos featuring the marine corps craft. To buy its only about $25 (£15). Well worth a look.
I am building exactly this same model, but am sticking with the 1st cav decal set as standard with the kit.
Are you detailing it at all or just building it out of the box?
Doug