Help me understand rebuild vs crate?

5cc of valve relief pistons. 1.92'' valves due to the small bore size. and being your first build-try your best to do everything right, take your time, and keep it simple. when u do it yourself every time you hear it run it is great!

5cc would give me 11.7 SCR. That seems pretty high, but at my elevation that should still be okay for 91 octane.