I would do something like this for a 12vdc vac pump. I think a vac reservoir is good addition too. Lots of room in the engine bay for say 1/2 gallon steel can. I like the idea of a demand switch so it doesn't run all the time. I would make the can out of steel pipe 3 or 4 inches in diameter and say a foot long. Big fitting for the hose to booster and a smaller one to the pump.
Amazon.com: FIQAPJ Brake Booster Vacuum Pum Compatible with Cadillac, Chevrolet Swift, Pontiac, Saturn-CTS, STS, Camaro, Caprice, HHR, Solstice, Sky Replaces# 20804130, 20939309, 31317530, UP28 : Automotive - https://www.amazon.com/dp/B0DP8GXNTB $41 vac pump
https://www.amazon.com/Alternator-Output-105Amp-Self-exciting-ADR0151?tag=ihco-20 105 A $65
You might need a different V belt pulley. One of the vendors up top has one that works with the toyota belts. He likely has the 1 wire alternator too. I would monitor the voltage and skip the ammeter.
2 days ago I'm driving to town and my ammeter suddenly shows like -20A. I get to nice place to pull over and investigate. Turns out the battery wire on the alternator had un-clipped. I pushed the connector back on, and ammeter read 0 at idle with the heater on high. Fixed in seconds.
My booster is bad, so I just hemostated the hose closed. I'm a big guy so manual brakes isn't an issue for me.