Agreed with most of this. In particular, replace the cam. A 2-bbl. engine with a 4-bbl. carb will "pick up" only a minor amount, and may actually HURT overall performance. If compression is "high" (over 9.5:1), use something like a Melling SPC-7 (068 Pontiac cam) or SPC-3 (744 Pontiac cam). If compression is lower, use Comp XE256H or (a little "bigger") XE262H.
The factory Q-Jet intake is excellent. Unlike other engine families, Pontiac did a good job engineering their manifolds. The 350 doesn't "need" the 800 CFM carb, so an earlier Q-Jet (pre-73) would be ideal. One with "notches" cut in the secondary air valve are intended for "performance" use, and may be the best choice.
