Ok, I am taking a 4bbl carb 350sbc out of an 86 GTA and putting it in an 86 Iroc-Z. Now the Iroc has the 305TPI motor, what do I have to do to make the 350sbc 4bbl work in the Iroc-z? Do I have to swap over the computer or what?

Welcome aboard thirdgen.org.

3rd gen carb'd cars never came with a 350. Was the original 305 replaced with a 350?

Is the carb computer controlled? If not, you don't need to switch the computer, because it's basically brain-dead anyway.

You will have to do something about fuel delivery. The TPI in-tank electric pump puts out too much pressure, so you'll either have to get a return-style regulator like the Mallory 4309 and knock the pressure down to 4-7 carb PSI (and it has to be a return-style reg or you'll burn out the pump), or remove the in-tank electric pump and use either an in-line electric or an engine-mounted mechanical pump.