300 passes was Bill Jenkins' limit as well
I am surprised the rod manufacturers don't trust the general public with some accurate method of determining a life span of thier aluminum rods.
Some formula based on piston weight, piston speed and any other factor that has a mesurable affect on rod life would be great. There is a great deal of difference in actual life span between a pro stocker and a lawn mower!
Take for instance a motor i built back in 1986. 440 stock crank offset ground to 4 inch with a 2.100 sbc bearing. BME 396 forging rods made up with 7.15 c to c length. This motor never saw more than 6500 rpm and had a very light piston. I bet the life of those rods was(or is!) Thousands of runs due to low rpm, moderate stroke and light piston. I ran into the guy i sold that shortblock to about ten years later and he said it was still running great!