Upgrade manual disc to power disc , but no room

There used to be units called a "hydravac" or "hydrovac." These were a vacuum boosted unit that mounted down on the frame. You used your regular master, fed hyraulics to the booster, and it automatically boosted it with vaccuum. I do NOT think they exist (unless aftermarket) in tandem systems These were popular add-ons for light trucks and old Jeeps




Another thing you might Google up is "Hydroboost." These are a booster that operates off a power steering pump. There's a member on here selling brackets. One source for small ones like you would need is a Chivvy Astro van



Otherwise, you'll have to find an offset bracket and possibly a small diameter booster unit.