I believe its personal preference. Below are the stats I give it:
Attack : 25
Def : 12
Movement : 9
Ability : blizt
Shield : same as modern armor or higher
Resources : Iron, Aluminum, Oil
First of all I believe a modern asault heli is as powerful as tank (and thus the same attack strenght as a modern armor) but defense wise due to all those sholder launch missiles a heli is pretty vulnerable and as such I give a def thats much lower than those of a mech inf
As to movement, I make it an Air unit with blizt. This will depend on whats your movement of modern armor (mine is 6 ) so I say give it 1.5 of your armor's movement
Shield cost let it be the same as modern armor or maybe higher take into consoderation the training cost of the pilots
Now, resources is again personal preferences. At the minimum its Aluminum & Oil. As for me, Iron is needed even for Jet Fighters so of course its needed for heli in my own mod
By the way, I assume you have fixed your animation probelm already?