hey, I actually had a similar issue about a week ago. I kicked off my edelbrock quadrajet and threw on a 650 holley. I know you're going higher than a 650 but this may also help. Basic rules of carb switching, Check all Vaccum lines, floats, and also check your power valves to make sure you're not flooding out your carb. I had a power valve that was to large and I had to drop it down just so I could stay running. also, Most of everyone here may know this and is well experienced with cars but, Those vaccum lines at the back of the carb running to the master cylinder.... yeah those are important too... ahaha... I didn't reconnect mine at first and tried to seal it off.... Don't try it... not worth it! besides all of this. if it's not a new carb, simply try rebuilding it *shrug* couldn't hurt anything more than your wallet, and the engine/carb if you rebuild it wrong O.o I trust you though, I mean hey, you were smart enough to ask these guys