Depends how much you want it to surf and power input. .
Normally at your weight I would say 150 Mako is big enough for general riding but you have added 2 criteria which change this. Really light winds is King territory as is wave riding
The other consideration is the king is the best Mako in mutant mode and is also good fun strapless
normally, yeah i’d agree & say the 150 for a guy that size, but recent feedback from a mate of similar size, is just LOVING the 2013 King he just got ... says it doesn’t feel that long - riding it in mutant & with smaller size kites in light wind is stoke d !
But it don’t really matter - you’ll have fun on both the 150 or King - just a matter of how much fun !