Only trouble with upping his PC is the effects of "in - game fatigue". Where a pitcher becomes less and less effective the more pitches he throws over his ideal limit.
I am a bit conservative, so I said 45/55, but yeah you could easily go 60/65 without too much worry. I'd be uneasy going past 70, but if you do so, I'd be interested in hearing how he does.
He'll be 100% the following day, but many of us feel that pitching a guy the day after he returns to 100 makes for a better start. Some do not.
So every other game @ 4-5 innings is sick and projects to like 320-400 ip. That'd be a heck of a fun experiment, seeing how close to 400 he could get.
But even every third day he'd push 300 if you were to take advantage of all the off days, which is still a horse by anyone's definition.