I primarily changed it out because I didnt like the way that the carb was running. Wasnt happy with the product, and it was borrowed. (had to give it back)
As for the manifold, It had two spots for a EGR valve, so it needed two blocker plates. I could also tell that it was restricting the hell out of the motor.
And I did specify that it was in a chevelle. (i double checked)
Once I put everything on, it ran great. I reused the thermostat, prolly a bad idea, but it didnt give me any issues prior to the swap.....