I ran some samco blue 3mm ID silicon vacuum hose from the red pipe to the gauge. I just popped the end off the red hose (the brown elbow) and pushed the plastic hose up inside the silicon hose at that end, and at the gauge end I just stretched it over the gauge nozzle. Had to stretch a fair bit but it went on OK.
I have left the elbow with a screw in the end to block it off, cable tied onto my fuel hoses in the engine bay so that if for any reason the gauge end splits, I can just pop the plastic vac line back into it the elbow to avoid a vac leak.