I get it for free bizzles
42/15 is a pretty common set-up, shouldn't have a problem with it. I'd try out both.
Im 5'8, 145 lbs (so by no means big) and running 49/16, got a new soma 15 Im about to start using. It pretty much covers everything I need to ride in the atl. Its a little slow off the line, but it def gets 0-60 in sub 5 brah.