I just installed one on my 1972 Grumman Olson Kurbside step van which was built on a Chevy P30 platform with a 235 in it. It was a direct swap for the single stage pump. Although, I did have to click the fuel side so that the fuel lines would match the position of the In and Out of the fuel pump.
I have a splitter for the vacuum lines in the engine bay. One port on the splitter is labelled MAN. That takes a vacuum line from the manifold. Another port on the splitter is labelled V.P. That has a vacuum line going from it to the OUT barb on the vacuum pump. Finally, there is a hose going from the IN side of the vacuum pump to a tee which connects to the port on the splitter that goes to my two wiper motors. There is a fourth port on the splitter I have capped off that would be used if I had a windshield washer bottle.
The splitter has one way check valves built into it that no longer work, so I used external one way check valves instead. My wipers now work well at idle, and under load.
I've attached some pics, hoping they might help you out.
