I am making a little top hat shaped piece to weld into the oem oil filter top in this picture. It has a 1/4 20 blind tapped hole in it. I neglected to take a picture of the finished piece, so you will have to use your imagination.
In this pic I am boring a counter bore into the top for the piece in the previous pic to sit in.
Here is the top after welding, grinding and sanding. This top mimics the 48/49 style of oil filter and screws onto the oil tank, instead of having a bunch of ugly brackets. This is for Tim's 46.
Here is what the inside looks like. I still have to have it polished, but you get the idea.