I'm no expert but I'd say that's a little big. I'm 5'9 130 & have a 156 k2 raygun. I love it but its definitely right on the edge of being too big for me, I definitely wouldn't go any bigger. So being a few inches shorter & 10 pounds lighter a 156 may be too much for you. But I'd wait for some of the more experienced people on here to chime in before you make a decision.
Btw, why the heck would he want to stop snowboarding for skiing? Oh well, your gain I guess ha.