Too Much Carb?

Hi, Have run out of money and a friend gave me an 850 holley with a rebuild kit. I want to put this on my almost finished 340. Everyone tells me to much air!!!!!!!!! I say with an XE268 H cam which was much more cam than the 340 6barrel came with and I believe the 6 barrel was around 900cmf? What do you guys think ? {street car with headers and X heads} Can I change the jets down to work if it is to much? Thanks your mopar brother Walt :shaking2: