i'd say you're kind of on the line and could ride either.
if you were riding lots of steep stuff i'd say just get the 156 but most of the japan stuff i've seen looks on the flatter side, so you might want the 160 for some more speed/float on the low angle stuff... the hovercraft is a bit on the slow side.
if i were you i'd probably go for the 156, because i personally like to ride shorter boards as long as they stay up. i'm 150# and could probably ride this board in a 152 if they made it (155 Heritage is my all-around)
get the hell off my lawn.