Welcome to the forum. Sorry your motivation to greet us is because of a problem.
Yes, coolant is getting into your oil system - no doubt. The only way to check a Pantera's coolant level is with some sort of dipstick placed into the overflow tank, so it is difficult to really see how much you are losing.
The Cleveland is a dry-intake manifold engine, so sadly that removes your leak from just being an intake manifold gasket issue.
That leaves head gasket or head/block crack. John's suggestions are good and may at least put you on the right side of the engine.
In most cases, if you are pretty sure what head is the trouble child, you can carefully pull the head and you will see the gasket problem area. If that is the case, you can then be pretty sure that is the problem and not a crack, and your fix will be a new head gasket.
If you have basic tools, good skills and a bit of nerve, head gaskets are not rocket science.
There are other owners in your neck of the woods that you might be able to enlist for help. They may chime in on this thread in good time.
Keep us in touch with your progress and don't be a stranger.
Larry