Captain America
The official Marvel site has Cap at 6'2" and 220 lbs. I think he's viewed as more of an athletic build than a really thick powerhouse type build.
http://marvel.com/universe/Captain_America_(Steve_Rogers)
(I'll probably regret posting this but anyway...)
Personally, I think he can pull it off - I don't know how tall/heavy Capt is supposed to be but I think Evans will fill out the suit. He might still have to put on weight - but he's not as scrawny as John Krasinski who was also rumored - I'd agree if you said he needed to wear a rubber muscle suit.
This guy?
I dunno
The official Marvel site has Cap at 6'2" and 220 lbs. I think he's viewed as more of an athletic build than a really thick powerhouse type build.
http://marvel.com/universe/Captain_America_(Steve_Rogers)