Vacuum gauge reading

[pinzinator]

What would be considered a normal reading on a vacuum gauge when connected to the intake? How steady should the needle be on a good engine?

[rmel]

Assuming your vacuum gauge is calibrated in Inches of Mercury, at idle 800 -- 1,000 RPM should be about -17 to -20 InHG.
MAP readings are going to be strongly dependent upon load and RPM (and leaks).