I dont see you gaining much by ANY header, now that you already have the h-pipe. If you do want headers, get the 1-1/2" EL shorties. They fit easier, and actually help low end, and not gain (as much) top end, but with everything else stock, there really isnt much top end anyways.
Here is the 1-1/2 that I used (and sold when I went to lungtubes for my 500hp combo):
Puilleys are worth an honest 7rwhp on the dyno (been there, done that), but you may have some low-charging issues...