I have read elsewhere that the header pipe diameter should match the diameter of the exhaust valve. 1.81 valve, 1.875 (1 7/8") header.
I run TTI 2" pipes, but I'm almost at 500 C.I.
The 5903 headers are cheap and worth it. They hit the left torsion bar and the collectors point straight back. My TTIs clear everything and the collectors point toward the clearance humps in the t-bar crossmember. If you can live with some compromises, the cheaper pipes are one way to go.