Replying to Question about what length of ski to get

Hey guys, I'm a snowboarder who is crossing over to skiing this year and am not too sure which size ski to get. My friend who is a skiier is telling me to get 160-170cm skis since I'm only 5'9.5". The thing is though is that I'm pretty heavy at about 215lbs. What size do you think I should be going for? The main models I am looking at are 1080's, PE's, and trouble makers, mainly because they are twin tips and aren't too expensive.
Thanks.