Is there a possibility that the engine is from a former military application? I had a M-151 Jeep once that had what appeared to be a vacuum boosted fuel pump which was actually a small air pump. Its purpose was to keep a slight amount of positive pressure in the crankcase when a snorkel and a high exhaust pipe was attached for deep water fording- - - -keeping water out of the engine while it was totally submerged. Pressure lines also went from that pump to the distributor and the alternator. As long as the driver could keep his head above water, moderate-depth flooded roads could be negotiated.
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!