What goodies do I need to build a Fast slant 6

So there you go, and for your first post as well.
Welcome to the Forum, I hope you stay with us.
You need to explain what car you have and what you want to do with it.
The are some here who don't like a slant, so you are going to get the V8 answers.
But 300 from a slant is not going to be easy or cheap.