If your rocker supports broke it was either a defective one or an install issue. Plenty of high hp motors running around with stockers. Make sure they take a good look at the lower rocker box near the valve springs as that is where mine rubbed bad against them and made some of my noise. The rest of the noise was the non-tapered adjustable SE pushrods rubbing inside the pushrod tubes, I don't know if that was an install issue or not but I went with the tapered SE's just to be sure upon installation. You probably have non adjustable so if they rub it is a install problem. Yes I have the same heads as you, oh by the way my valve guide seals were no good in less than 2000 miles. After getting the proper clearance around valve springs and eliminating pushrod rub my motor is stock quiet except for the exhaust note!

 

So I looked at the rocker supports today. The one in the rear was litterly cracked into 2 pieces. A quarter of it cracked off of the entire unit.