The older MOTOR or Chilton manuals give the proper procedure for a compression test. Did you block the throttle open on the carburetor when you ran the test? Did you have all the plugs out, or only the one on the cylinder you were testing? Did you go back and squirt oil in each cylinder and check it again? Has the engine sat idle for a long time? (The one cylinder with 70# might have a sticking valve.) Not trying to be a smart a-- but if you did it all correctly, it STILL seems to be a drivable motor, and it gets real costly to overhaul one, especially if it doesn't need it. I'd run the valves again and drive it.
