400's are they any good?

I dont like the Procharger idea... It's cheap, but takes a ton of power to run and puts a lot of stress on the nose of the crank when you start adding boost. If you are building for 1000hp, then buy a real (aftermarket) block. If it's more a question of I want a solid BB B wedge in my car, build a 470 N/A and get a top end that will make some power. Bigger cubes than that and you get into some very short pistons, and again, you start losing power from ring sealing issues and you lose longevity. You have a base 400. If you want a modern build, use aluminum closed chamber heads, build for quench and dynamic compression. Have top quality machining done. I dont think 8K rpm is needed or realistic, but some people just want to be able to. In order to do that regularly, you'll have to do some oil system work and run a light crank and really good light rods. If you want to buck the system, stick a turbo on it, leave it at 400 cubes, and you can make an easy 1000hp fairly reliably. Until the main webbing fails... which is why I say use a better block from the get-go if that's your goal.