you can ride any ski in the park if you really want to, but that is probably too big for a pure park ski. i would say anything up to 100 for a pure park ski, 100-115 for all mountain/one ski quiver, then 115 and over for pow skis is a (generally) good frame of reference IMO
"I think safety meetings should be mandatory, as skiing the park can get a bit dangerous some times. Just mellow out with a saftey meeting and everything will be safe and smooth." -John Ware
I'm going to weigh in on this because I've skied everything from 82-127 in the park and am (slowly) coming to a conclusion.
115 + is a powder ski. They are skiable in the park, it's fun occasionally but for every day it's a lot of weight to be hucking around, makes it way harder to learn most tricks and I flat out am too scared to try some tricks I know I can do due to fear of not getting them round.
100-115 is manageable as an every day park ski if you ski a certain way. For butters/presses/surface swaps this is a perfect size, for spinning on and off rails and bigger spins on jumps, this is still a big ski. I am currently riding Line Sir Francis Bacons as a 1 ski quiver and finding them a lot of fun 80% of the time, but limiting when I want to try a small handful of tricks.
90-100 is the perfect pure park ski size for most people. Narrow enough to not limit your spin tricks but wide enough to feel stable on rails doing surface swaps etc. Best of both worlds for me.