1971 360 question

Just an update, the Holley 750 works perfectly and the car really responded to it. The vacuum is 10 and the power valve was a 6.5 so I installed a 4.5 and everything works great. The only issue I'm chasing is the idle. I set the timing and adjusted the idle mixture screws, but the idle in gear is about 700 rpm and in neutral, it's around 1100-1200 rpm. I'm thinking it's a vacuum leak somewhere.