I think the easiest way to achieve this is by using a few already existing items in the game. It would be easiest to make him a rigger with a drone (Since they talk about how powered armor tends to kill the pilots), and modify the drone to fit. I'd use the following drone to make it easy
Mitsuhama Otomo as the base of the model. Allow him to add a pair of lasers to the arms, since the arms can be modded to be like cyberlimbs. Add a Fixed remote weapon mount with the GE Vindicator minigun, and another one with a Mitsubishi Yakusoku MRL. Now I know in the movies he only had assault rifles on the arms, but I prefer the comic version where he had repulsors, and the missile launcher is just another thing he had in the comics. He's going to spend a metric drek ton on outfitting the drone, but it allows him to "suit up" as a War Machine knockoff. As for the flight system just allow him to use a jump pack of some sort, or allow him to install a flight system that uses 4 slots, and gives the following stats when in flight,
Acceleration- 40/60
Speed- 200
Handling- -3 The reason for the poor handling, look at the amount of time it took Stark from the first iron man to learn to fly the suit. One mistake and he ends up going where he doesn't want to. He gets hit while in the air, force him to make a Pilot check (3) or it crashes.