I found the right fittings at a local auto parts place [Baxter's]. They are a strange sort of one piece compression fitting, no ferrule. When you snug them down, the nose of the nut squishes down on the tube. Hung a spare gauge outside firewall temporarily just to be safe. So after several long seconds of cranking; Eureka! we have oil pressure. Thanks to all for advice. And then something discouraging happened that I will pursue in a new thread.