Theoratically this should work?

ok, I'm thinking about removing the smog pump. At this time I'm doing a complete engine overhaul. I'm also purchsing an off-road (no-cats) flowtech 2 1/2" X pipe and flow master mufflers for my exhaust. While cleaning up the heads I noticed a passage on each head that the smog pump pushed air through to mix with the exhaust. While cleaning these an idea had occured to me to just block off these passages and put a free spinning pulley in place of the smog pump. Would this alone trigger the o2 sensor's to lean my a/f mixture? I think I remember hearing something about false reading o2's that give the computer the info they want to hear? Would this alone me sufficient to run this type of set up, or would this somehow cause high engine vacuum or high manifold pressure?

your talking a 5.0 Mustang right?

Yes, 89 Gt Fuel injected 302.