On a big rig there's usually enough room to add a vacuum reservoir tank- - - - -the bigger the better. That usually eliminates the need for a vacuum booster fuel pump. I like repurposing medium-sized refrigerant gas tanks mounted under the bed or inside frame rails, with one way check valves to store enough vacuum for a few brake applications if the engine stalls.
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!