Jay,
If you want to improve on the action of the wipers, you can add a vacuum can. On the M-37, the vacuum comes from the manifold thru the double stage fuel-vac pump to the wipers. If you are missing the fuel pump or running an electric pump the vacuum will vary depending on throttle position. Remember that the vacuum takeoff is below the throttle,so if the throttle is closed, like at idle or steady speed, the vacuum will be high. As you push on the throttle to climb a hill or go faster, vacuum drops. What I plan to do is install a can and T it in the line behind the glove box. I also will install a check valve to prevent the maniford from letting air in under low vacuum conditions. Look on e-bay for a Trico vacuum can or make one by putting one small hole in the top of a 2qt. juice can and a larger one on the bottom. Wash out the juice and solder or epoxy the top hole. Glue or solder a 1/4 inch fitting on the bottom, paint black, and it will look like a Ford vacuum can.
Mark