Speedway motors sells heads that are based on the same pro-action model as does many other. I'm not familar with this company, They seem to make a good sale and their prices seem good also. Just not sure how they stand behind there product, I'd check into that. here's a link to speedway motors they have alot of things that may intrest you Including alot of helpful charts and tip when you search different parts.
http://www.speedwaymotors.com/default.aspx