Anywhere that gets full manifold vacuum would be a good choice. Don't use the ported vacuum that goes to the distributor. The port on the side of the manifold where the vacuum wiper hose attaches would be good, or a T fitting at the manifold side of the PCV would work well.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!