The LS motors have a stronger bottom end. The old 2-bolt main SBCs were only good up to about 500 hp. A 4-bolt main block might get you a up to 700 hp, but really want a main stud girdle for anything 500 hp or more.
The LS heads also have a superior architecture. The Vortec heads were the best factory heads, and they're handicapped against the better LS heads. The way you make an engine with poor flow competitive is to make torque. It's similar to the 440 vs. Hemi debate. If you're racing, there's nothing superior to a Hemi because their heads flow so well, but they can't make the torque that a 440 can.
If I were building a track car, 6.0 all day. If I'm building a truck, 5.7. If I'm throwing a chinese turbo on a junkyard motor, the LS will take the abuse. If I'm building from scratch, I'm confident I can build more performance cheaper with a 350.
The LS heads also have a superior architecture. The Vortec heads were the best factory heads, and they're handicapped against the better LS heads. The way you make an engine with poor flow competitive is to make torque. It's similar to the 440 vs. Hemi debate. If you're racing, there's nothing superior to a Hemi because their heads flow so well, but they can't make the torque that a 440 can.
If I were building a track car, 6.0 all day. If I'm building a truck, 5.7. If I'm throwing a chinese turbo on a junkyard motor, the LS will take the abuse. If I'm building from scratch, I'm confident I can build more performance cheaper with a 350.