to echo what Allen said on the carbs, i've heard the dual SUs are the best option for Z-S conversions from other sources as well.
Also, to clarify, 1977 cars did not have a 3-2-1 header as earlier cars did. It was a 4-1 POS. Same with the intake manifold. I've heard VERY mixed results on aftermarket headers, shoot for an OEM design as Allen mentioned.
incidentally, the only reason i sold my 74 B GT was because of rust, the mechanical bits didn't scare me!
