What does a "stock" factory street hemi cam spec at for duration and overlap and what does a "stock" Hemi have for idle vacuum? If the Comp 292 is anything close to the MP 292 cam, spec wise, I wouldn't expect idle vacuum to be much higher than you are at 426 cubes.

Probably an apples to oranges comparison but my 493 wedge has an MP509 that has 76 deg of overlap which is the same as the MP 292 Hemi cam. It idles at 7-8" at 1100 RPM.

As for 15% leakdown, my builder considers anything over 10% worn out on a competition build.

Kevin