Too big of cam?

agreed, check all your tuneup type adjustments and make sure everything is where it is supposed to be (timing, points plugs, wires, vacuum lines, etc), check for vacuum leaks where the intake manifold bolts to the head, and the base of the carb. the cam you have is going to have a noticeable lope to it but it should run ok and perform decent. I have a 4bbl intake I would sell if you think you want to keep the 6, I'm in the process of changing to a 318 as we speak.
report back after you tune her up a bit and let us know how it's going.