help found oil in coolant

[Falcon 269]

If the motor's running fine and not overheating, chances are the head gasket is fine.

I'd start by draining the coolant, flushing the system and refilling.  Clean out the header tank and see what happens next.  If you get more oil appearing, you've still got an issue somewhere.  If not, it's a mystery but one that isn't indicative of a real ongoing problem.