huh ... I thought pumps with vacuum fittings were for wiper boost [one line to manifold below carb, one to wiper thru firewall], be odd to have anything from that hooked into the crankcase, although it wouldn't be suprising to have a check valve on anything that did - might have something to do with a PVC mod for 58? I'd see if the 'loose' hose was sucking or blowing, if it's not capped off ... and do you have vacuum wipers?
Bill