This topic looks like the appropriate place to post this.
A couple of years ago I bought an oil filter adaptor online from J&P Cycles, a large parts seller for all kinds of motorcycles, but not really vintage British. Vintage Harley, yes. Anyway, when it arrived, I thought it was much too large and there was no way I could or would fit it to the bike.
Now, on the verge of completing engine repairs, I wanted to run with a filter right from the start. Back when I bought the large adaptor, J&P was very gracious about taking it back for total credit, but now, a restocking charge and more shipping cost. I'm feeling cheap right now, so I decided to take another look. The photos show what I came up with. If I decide I don't like it, it will be easy enough to remove, leaving no trace. It is held in place with a bespoke bracket under one cylinder base nut (for now).
Oh, the install needs to be cleaned up and, no, I'm not going to try to run without a feed pipe.
Richard L.