You have a carb that was designed to be used in pairs on a tunnel ram. It's not a good carb to run on a single 4 barrel and is really an ON/OFF style carb.
Your jetting is horribly imbalanced with an 85 front and it has the stock plate in rear. It's jetted 85/73 if I'm correct. That will not make the engine happy.
If it was me, 750 DP and a 1" open spacer and I'd bet it will run much better
