Tuning after headers??

Hey guys i have a 318 that i just put headers on and i have a holley 600cfm carb. After i installed the headers when i get on it it does bog down it just does go like it should but when the secondaries crack open it just rockets. Should i lean or rich the mixture to make it go better? Also would a 650cfm double pumper work good on it? I can get one from my uncle for free but unsure if it will work better or not. Thanks guys!