Need input from big cam users.
What settings are you gonna adjust the valves to. I would go to a loose generic setting like .022 int. and .028 ext. and see how it respondes. If you still have low vacuum at that point i think you need to look at the chain and possibly degreeing the cam in.
P.S. i've run
[email protected] cams that i retarded a few degrees to take some bottom end out of them for street tires and they still pulled 10-11" of vacuum. And most .480" cams don't have more then that kind of duration.