[Danr55]

Have you measured the pushrods to be sure they are the same length? I know that photos make things look like something they are not, but the two shown here sure appear to be different lengths.. Have you checked the length of the rocker arms to be sure that you have the right ones for the heads you are running? All of the pushrods appear to be rubbing or close to rubbing on the head port. Either of these issues can create a situation that will work for a while.. right up until it fails.. Much like what happened here. Having screwed that pooch, I know all too well.