Hi Guys,
My 2c worth. At 70kg, anywhere between 132 and 134 would be perfect depending upon how powered up you ride. 2cm will make bugger all difference, it's more about the width than the length. 39.5-40cm wide will be ideal for that weight range you speak of. The wider yo go, the lighter the wind you can get away wth, but you sacrifice control at the upper end of wind speed.
Some great boards I recommend: North X-Ride (freeride), North Jaime (Free ride/style), North Select (Ultimate full carbon freeride), Core Fusion (Excellent full carbon freeride), Best Armada (Carbon crossbraced freeride), Best Pro-Creator (Carbon free ride/style), Cardboards FR (Only available second hand now

)
Of this bunch, ranging in price from $899 to $1450, the 2014 Select is the most expensive, but the most amazing board I have ever ridden, the X-Ride is possibly the most popular high quality board freerider, The Armada is amazing for the price ($899) and holds it's own again much more expensive boards, the Fusion is possibly the best value, super lightweight, full carbon board, the Pro-Creator is my new personal fave after riding it at the Best dealer meeting, love it!
Lots of great boards available these days, demo first, then buy with confidence.
DM