Technically, I doubt I've pushed it much further than 66%, and even then it might have just been 65 because I was using more starter for a 24 dough.
I'm typically at 63. I've been on a pretty good streak lately, so right now I'm just trying to nail the consistency for a 24, 48, 72 hour dough. I keep playing with the yeast percentages until I get a dough I like. If I've learned anything it's that you only alter one variable at a time. This pizza thing reminds me a lot of fiddling with a golf swing.