I'm not sure if you meant me or Dan, probably Dan, to respond, but any way here is what I think:
"Lunati 41199LUN, same as 411A1LUN other than LSA, solid flat tappet, .558/.580, 238/248 @ .050, 272/282 Adv., 110 LSA installed at 106."
This cam has a very moderate overlap number of 55 degrees. 55 degrees is on the lower end of high performance street cams. Many high performance street cams that came from the OEM's had higher overlap numbers. Normally a cam like this should produce a reasonable to good amount of vacuum, probably in the 14-18" area. However, what you have working against you is the higher amount of duration @ .050 (238/248) which essentially means that for the amount of time that the valves are open, which is on the medium side, a lot of mixture is being allowed into the combustion chamber due to the aggresive lift of the lobes. This is normal for a solid cam. The more densely packed cylinders of an engine with more duration at .050 will contribute to more low end "grumpiness" during the low end reversion process that occurs during the overlap phase. As reference, 238 degrees of duration in a solid cam looks more like 230 degrees in a hydraulic cam due to the valve adjustment needed for the solid lifters (the gap, so this cam looks like a 230/240 hydrauic cam, generally.
What compunds the problem further is that this is a relatively high lift cam, also. Again, more charge being allowed into the combustion chamber will cause the idle characteristics, and vacuum, to worsen. Think of it as having a window in your home open during a serious rain storm. Will more water get into the home if the window is halfway open, or all the way open? (That's a rhetorical question) Clearly with the window all the way open more moisture will get in. Similarly, if 2 cams have the same advertised duration but one has higher lift and more duration at .050, the one with more lift and duration @ .050 will have more negative effects from overlap because there is more mixture to back up into the intake at idle and make it "grumpy", "choppy", "lopey" - you pick the descriptor.
Essentially, what I'm saying is that although the cam may have only 55 degrees of overlap, it probably is going to act more like a cam that has more overlap because the lift, and duration @ .050 is a little more aggresive.
However, having said that, I think that 10" of vacuum is low, I think that 12" at 900 RPM's would be the low end of that cam. This is a fairly popular grind, one that many people purchased and used through the old Crane Cam's company - I think it looks a lot like the old F238. Maybe start another thread asking what people remember this cam to idle at and what vaccuum it pulled. I'm sure some people are still using this cam from Lunati and Crane and the Lunati cam that you have.
Also, many of the issues around vacuum at idle revolve around fuel delivery or ignition. Have you tuned for vacuum? If you have those 2 systems checked (fuel and ignition) then you have to begin looking at any other area in the motor that is allowing air pressure to escape and therefore decreasing the engine's ability to creata a vacuum.
I hope this helps (probably not), and I think you should poll some other folks on this site who have used the same of similar cam and see what there reults are/were so that at least you will have a baseline.