I have a question, I want to know which type of header I should use on my 455 olds big block? I have a delta 88.. Not sure if I should with shorty headers or full size.. Can anyone help with this question?

 

There are no headers commercially available for the 65-70 Olds big cars, regardless of what any catalog says. Custom headers are prohibitively expensive (in the $2k range).
If you want dual exhaust, you can purchase the correct reproduction left side exhaust manifold for duals from Thornton Reproductions.
http://www.themotorcompany.com/Full-...d-p-16158.html