how much power will stock rods survive?

when i was circle track racing my 360 with slivolite pistons I had the lighter "273" rods in it to save weight, I also had the crank lightned and internaly balanced. this combo would see 6500 and back to around 2000 around 100 times a night and I was never worried about the rods. when i did blow it up it was beacuase a valve broke at around 6500. every engine failure i ever had in 10 years of circle track racing was caused by valve train falure. I blew up a 340 once beacuase a rocker broke and the lifter jumped out of its bore. THIS CAN BE A REALLY BAD THING!!! lol you cant just shut it off in traffic when something sounds wrong and it took me about 1/2 a lap to get off the track.