I would highly recommend Bill Cornick, who is on your IAC list. Twenty years ago I worked with him on initial aerobatic instruction for all the manuevers in the Sportsman category. He is an excellent instructor and one of the finest aerobatic pilots I have ever seen. I watched him practice his unlimited routine one day and it was better than any airshow performance that you could hope to attend.
Santa Paula is a good airport to fly out of as the aerobatic box is not far away and it isn't crowded there during the week. Lots of cool airplanes tucked away in the hangars as well.
Typhoonpilot