Re: Flush header
Hmm --- now if you have engineered roof trusses that bear on this wall adds some complexity. In that case the bottom cord of the truss is typically the ceiling joist and would require those trusses to be engineered / approved to be modified for hanging from the header.
To add to Sprucey's point about having the architect to evaulate and possibly provide the necessary engineering --- since you are altering structure you need a professional enginner's stamp of approval for the building permit.
Most things can be done if you are willing to pay $$$.
"" an ounce of perception -- a pound of obscure "