Ok, so what exactly are you thinking in terms of army builds, roughly?
I'm assuming something like this:
Detachment 1: Spearhead detachment, has all the tanks and other doctrine breaking vehicles, maybe runs as an emperor's fist company from time to time. So, two tank commanders, a few more russes to build up the list, and then some hydras and artillery to deal with aircraft or long range targets. Cost of about 1300 points or so.
Detachment 2: Battalion detachment as a Tempestus Drop Force, with some HQs, 2 or 3 sqauds of scions, and a pair of valks. Cost of about 600ish, more if you splash in some heavy weapons on the scions.
I think this explains why I'm suggesting not trying to the warhawks and scions thing, I just don't think you'll have the points for that if you're also wanting tanks and other heavy support assets. You could make scrounge enough points for a patrol or even small battalion, but you'd be stuck on foot and it'd be tricky to fit more upgrades into that group, and I think fitting them in would cost you too much, both in command points and in what you could have brought in the other two detachments.
Oh, and if you want warhawks, I'd still suggest Anvil as your first choice,
but this guy also makes some.