compression test question

I would try changing the valve seals before springing for a full valve job. As old as that engine is, the valve seals are probably hard and brittle.

You can change valve seals with the heads on the engine. You just need to rig up a way to put compressed air into each cylinder. I was able to connect my compression tester fitting to a compressed air coupler. The compressed air holds the valves closed so they don't fall down into the engine while you remove the spring and replace the seal.

While you have compressed air in each cylinder, check for air leaking out the carb or tailpipe which would indicate bad intake or exhaust valves.