the 20v header (or whatever header) will only bolt onto that block? cuz it looks so damn cool! i love lookin at it! screams pro-stock!

There are 10v (normally aspirtated) headers out there. There is also the "other" 10v header out there, with an extra flange for a pesky hair dryer, several variants ;-)

They are typically "home made" meaning cut-n-welded el's and such, but they are generally similar looking due to the space contraints.