I've seen older research that stated 60-80% for power development so it looks like that hasn't changed much. However, I believe that is the range for improving power output that transfers to sprinting, jumping, etc. If you want improve at cleans/snatches them I think you should approach it differently.
I use more than my max when I do pulls. I don't do a high pull though; I stop at the shrug. I think the height of the bar has more to do with the power generated from the hips; not the pulling you do with your arms.
If what you've been doing has stalled then try a regular pull with 100+% of your max instead of high pulls. I recently power cleaned 315 and I was doing pulls with 345 leading up to that. My max prior to that block of training was 295. My 20lb increase is probably due to adding the pulls; I hadn't done that with any structure in the past.