Don't know of a write-up on the Smedspeed conversion but I fitted one to Miss November so there's pictures and discussion on my build thread, starts about here:
https://www.xs650.com/threads/miss-november-xs2-tribute.55057/post-598561
Some people worry about the filter being ripped off by rocks - the filter extends
slightly lower than the frame rails but is well tucked away and I've never had a damaged filter in more than 10,000 miles of road use. I don't ride rocky trails. Personally, I value the reassurance of having a modern fine filter element keeping the oil clean.
So do I, the motorcycle trader in our village stocks Putoline so I can walk along the road and pick up 4 L of Putoline Formula V-Twin 20W50. I think the V-Twin formula is designed for old-fashioned engines with roller bearings, as opposed to modern plain bearing engines.
Mind you, his prices are going up so I might start to go on-line and buy Smith & Allan oil.