i'm 6' and 150lb, and I own
140 fks set at 8! for park and they hold me in no problem. Very shocked with these at how low I have them. I overshot a jump to just about flat, broke my shoulder blade and they still didn't release.
px12 at 10 on my bacons, no problems
axial 14s at 10 on factions, and again never released when I didn't want them to and did when I wanted them to come off.
I'm going to say that 12's would be fine for you in park, like on them skis said, unless your hitting massive jumps these will work for you. I don't understand why people have their sth16s maxed for park, one awkward landing from anything and you can seriously fuck yourself.