GM had so many setups, and the possibility of monkeying with the carbs is so great, it's pretty hard to know how it SHOULD look. Have you deceiphered the stamped number on the drivers side of the carb? Starts with "17" or "7". Plenty of decoders out there to tell you original application for the carb.
looking closer at the pics, it DOES look like something is weird around the choke. What is that thing blocking the lower bolt on the vacuum cannister mount? It looks like you could fit your finger in it! Any time I've seen anything mounted to the choke via that break, it has a simple slot/rod setup, identical to how the vacuum can is connected to the secondary air valve linkage in your photos.
It does look like something is also missing on the passenger side front of the carb, witness the two empty bolt holes. Like I said, there are so many variations, I'm unsure what MIGHT have been bolted there, if even used on your carb.
Does it run poorly now? I mean seriously, it doesn't matter what people say, if you can make it run good. Usually helps to have it hooked up as it was originally, however removing EGR, changing other stuff on the motor all affects how well the carb works, regardless of what some might believe or say. You only need to look at the thousands of combinations of primary rods/jets and secondary rods/hangars to know that it isn't a "one size fits all" deal.
