You could change,but WHY,that is a rare set-up on your Caddy and I sure wouldn't want to part with it.It should be set up with progressive linkage so you are only using the center carb anyway,unless you have your foot in it which will open the front and rear carbs together.You now have a win win situation,you win for rarity and the wow factor and you drive around on a 2bbl carb for economy so you win again.
I agree with Liquid, just use what you have, man there are a bunch of folks that would like to have that set-up. If something is wrong with your carbs you can just rebuild them and be as good as new. No way would I change what you have.
Well I'm not sure I read this right but if you have a three two set up on that cady, I don't care if it is oem or after market, it's got to be pretty rare and desireable.
Best advise is tune it and keep it. Very cool.