Technically it's not too big. However, it'll be like trying to maneuver a plank down the hill, it'll be a bitch in the glades or on tree trails, and you won't really be able to spin it. Also, a 160 or 164 won't be too small
'12 Lib Tech T.rice / '12 Burton Cartels
'10 CustomX / '10 Co2 EST
for reference use im 190 Lbs and my longest board is a 161 and it floats great in pow. I would think you might want something a bit smaller unless you plan to hit knee deep pow all day with that board. whats your boot size? if smaller then a 12 then the width and length would cause you to use alot more effort when edge to edge on groomers and such and you probably wont be happy with it.
For another reference, I am 175 lbs, 5'7" and my last day at Breck I strapped onto a 164 flow mercury.
Can I ride it down the hill? Yes. Can I get it going fast if I point it down the hill? Oh yes. Am I going to be doing 180šs or really tight, precise maneuvers through obstacles? Not anytime soon!
You won't notice the extra heft or weight much on groomed slopes or terrain that doesn't require much cutting here and there... but its not an ideal all-around board...and you'll definitely want to stay away if you haven't figured out how to turn properly yet