I like the oil bath, but I finally had enough of the oily mess mine always made. My '67 has the offset style with a separate stand, bolted to the pass side of the head and two wing nuts on top.
There is a big rubber gasket inside about 10" x 3/8" x 3/16" thick, that was torn. I tried making a gasket out of various materials and using different solicon and caulk, but it still leaked. I welded a piece of tubing over the hole in the center to act as a dam. The rod for the wing nut passed up through the tubing.
I tried it with the oil half way up to the mark, but it sloshed around too much even with heavy oil.
The things I did to it reduced the mess, but eventually the bottom of the air cleaner and the valve cover would get oily again.
I finally gutted it and put in a paper filter. It is now dry and staying that way. There is no way I would use a oily K&N mess now that it is dry.
This air cleaner has the outer sides that come down over the sides of the lower half. Now that there is no oil, I cut large holes to get the air in easier. They are just barely concealed by the outer cover.