His second or third post, he said, "It is a brand new internally balanced engine, and I sprung for the roller cam upgrade and other goodies, so I really can't afford nor want to start unbolting and replacing parts."

All this leads me to believe that it's a Muscle Motors crate engine. It could be a hydraulic roller, even.
MM's website isn't very specific about the camshafts.

The fact that it idles with quite a bit of vacuum tells me that it's probably not too big and the rest of you are probably on the right track with suggestions about timing, or else the carb is out of adjustment, something like that.

I'd still like to know what the cam is, though.

R.