Dean's right.

Find a way to get piston weight down to smallblock chevy country and those smallblock chevy-sized rod bolts will be able to handle it.

350 chevies and 318s have the same diameter rod bolts as any B/RB non-hemi connecting rod. The rod bolts are the most highly stressed part of the connecting rod.

So no more than a 550 gram piston with 150 gram pin and hold rpm to 6000, where the heads will not even be starting to work. That's no way to go fast.

You do know that the LY rods were the "standard" rod first developed for 413s, right? There is nothing special about them. The 3/8" rod bolts are the weak link, however after several million cycles the rod top end can rip off at high rpm as well. It's kind of a race to see which side fails first.
The 908 heavy rods added mass to the shank which helps eliminate the top ripping off scenario, but which puts more stress on the wimpy 3/8" rod bolts. So now piston weight is even more important. NEITHER is a decent high performance rod. 7/16" rod bolts are a must in a big block that is going to make power.

R.