At 5000 rpm, you will never have a problem.
At 5500 rpm, you will have more problems with rocker clips busting than rods.
At 6000 rpm, you are on borrowed time with rockers and rods.
Being a cast rod, detonation is very bad. Forged steel will give a bit, where cast won't. Cast cracks when is subjected to a sharp rap. Detonation produces the same symptoms of parts being struck with a hammer.
If you are still unsure of the rods duribility, a set of 455 Olds rods will give you the security your looking for. Hang a set of Keith Black hypereutectic pistons on them and you will be safe to the max rpm your heads will flow. In a normal asperation build, a stock head will peter out by 5000. If you go the ported route, 5800.
I just realized something from your last post..... Hehehe.......I told you to E-mail me if you had any more questions, or something you didn't understand. Know who I am now? Dan