I'd run a 4" pipe about 18" long. No need for any kind of bleeder valve- - - - -the vacuum will go away on its own within a few minutes of engine shutdown, and there's no problem with keeping some vacuum in reserve all the time. If you want to deplete the reservoir for some reason (can't imagine why) just pump the brakes a few times with the engine off.
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!