you can take those 2 temp actuated vacuum switches off your thermostat housing. the one on the right controls the AIR pump flow and heat riser. When its cold the flow goes to the AIR tubes on the manifolds, when it heats up it switches to putting air in the cat converter. the left one goes to the evap canister. I took them off and replaced the housing with GM part# 10108470. it was about $5. you can run the vacuum line going to the left actuator right to the carb when you take it off, so that your EVAP canister still works.

also, where did you get that trick looking EGR block off plate?

 

You answered the very question that made me come check this thread again. I wanted to make sure I could remove those vacuum switches. Where exactly did you get your part though? I've looked online and the only one I can find without the two threaded holes is at Corvette Central for like $35! Worst case scenario, I just buy two bolts to thread in. My block off plate came from Corvette Central, I think it was $15 plus shipping.