Unless your engine is broke-I wouldnt fix it! Sludge in my opinion doesnt count-as long as you have good pressure. You can tighten most of the oil pan bolts without moving anything(not too tight though)-odds are your leaks are not to do with the oil pan-probably your rear and front seals leak. Oil pressure sending unit is also a likely candidate (if your car has an oil pressure dummy light-cant remember about '69)-the little sensor that the wire plugs into is very prone to leaking. Of course-the valve cover gasket probably leaks a bit as well! Thats why old volvos last so long-they change their own oil! If the motor is not too bad-Id fix all the other stuff first!