A 240/600 load like a PAC 1243 or COMP 943 "should" be good to 7000 RPM (or higher), as long as the cam's not overly aggressive, the pushrods are stout enough, the rockers are rigid enough, etc.

One (or more) out-of-sync component with the total package and it might not matter what springs you use. And that same caveat likely applies to how things will hold up on the street, too.

Wish I could add more first-hand experience, but with all the delays getting much junk back on the road, I don't have anything to add for long-term durability.