What are the practical limits to the stock Magnum Rocker package?

I ran stock rockers and pushrods in a 360 magnum circle track car. I had a hughes hyd roller .580ish lift, and 2.2 Litre retainers with the Mopar performance valve springs. I would have valve train issues if I spun it up past 6000 rpm. Likely pushrod flex would take the rocker and pushrod out. Keeping it inder 6000rpm everything was good