YEah totally go the winter soldier route, brubaker made it pretty much made for movies. After cap has huge success on the battlefield the goverment want to give him a squad of soldiers, the allies put in the invaders( uniion jack, spitfire etc) and the US gives cap another american partner BUcky, maybe steve allready knew him maybe not, any way would be pretty awesome. Just do the propaganda piece too miex in with the covert spy/assasin bru made him in.
ANd my pick is for ben barnes to play him, he looks young and badass, JGL just looks scrawny