External oil pump pickup pan mod...?

Don't think that would work in this application. The bulkhead fitting screws into the pickup that sits flat on the bottom of the oil pan. The Milodon fitting shows an o ring and flat washer that I guess goes on the outside of the pan - like a drain plug - external sealing?

If you are talking about this type of pickup, you can also weld it to the pan, instead of using a bulkhead fitting to secure it. Then you just weld the bung over the same hole on the outside.

pickup.JPG