I have a 67'Camaro RS/SS 350 295hp. It currently has an aluminium Edelbrock Performer intake and a Holley/Model 4175/650 cfm/elect choke carburetor on it. I am trying to return the car back to the #'s matching original condition(as much as practical). What can I expect as far as performance and drivability going back to the cast iron intake and Quadrajet. Maybe another option is to put the Holley on the Iron intake. Pro's/Con's ?

The only performance loss will come from the extra weight of the iron intake which will be negligible. A properly set up Q-jet will run just fine and probably save you a little in fuel costs.