[Rev]

Use the port at the right front of the Holley. There are 2 ports there, one for manifold vacuum and one for ventouri vacuum. You want the manifold vacuum port. That's the one that will read some vacuum at idle (probably only 6-8" Hg with your cam).

I think you should use a 4.5 power valve ot there about since you really don't want it to actuate unless you put your foot in it some.

Rev