Alright guys, it's been a while since I did that research.
I chose the ZL-1 block over the Brodix-Dart-World for a few reasons.
GM Engineering- It's no secret that an Aluminum aftermarket block can cause problems and be high maintenence. Knowing GM endurance tested the block to THEIR standards was a huge plus. I've been very happy with my block.
Weight- It is lighter than the other blocks.(Just not as much as I thought)
Heritage-The ZL-1 is the ultimate 1969 Camaro. Clearly I don't have a real ZL-1 but it certainly doesn't hurt the value of the car.
Power and Economics- I could actually reuse a few of the parts from my first engine.
Mainly the pistons, heads, carb, and fuel system. Going 540 meant these part wouldn't work. When I mat this thing and row through 4 gears, it's on the edge of scaring my into soiling my pants as-is. 666hp is plenty for this chassis. Sure Mark is usiing 800hp but he's clearly the best driver around. Are you?
This all being said, I can understand why people choose the LS7. Technology is a thing of beauty. Factory dry sump, fuel injection, hydraulic lifters, no leaks, gas mileage, and weight. My combo isn't radical but I do need a mechanical cam to make 666hp/641ftlbs and control the valves up to 6800 rpm on a reliable basis. I would love to have fuel injection but that ain't happening.