Here’s a real ghetto-tech approach to the vacuum system.
Got a great drawing from this forum post, it’s the first drawing. I haven’t a slightes clue what parts 1 & 2 on the drawing are but nevermind, it’s all connected together and there’s no loose ends. Expect a follow-up on vacuum troubleshooting 🙂
Here’s a picture of the result. The big black roll of hose with the aluminium block is a shutoff valve, I eventually did install it inside the car.