I reused the stock bung and oil cap and welded that to a thick walled stainless elbow with a nice flange at the top. The notch in the bottom is for chain clearance. The vent on top has the rubber line coming down that points at chain.
The feed line at bottom, and the return line in top.
Here you can see the venting nub thing on top that was reused and welded in from BSA.
Loose one the floor, it looks a bit Android'ish I suppose, but when in place on the bike, it all makes sense & looks right at home.