Picked up a Ever-Ready 300PBT for a few bucks at an antique store. Sorry - no b4 pics. The diameter was 16mm and the pure badger hair was super floppy and had some serious funk.
With the fantastic advice from several members, I purchased a 22mm Finest knot from TGN. Cut the old hairs down, covered the handle with painters tape AFTER I gouged it a little with a drill bit. Went to the Dremel with a barrel shaped sander and opened the hole carefully to 20mm.
I chose not to weigh it down, which I now regret. Filled the handle with some epoxy, carefully set the know by eye end feel for preferred amount of flop. The end result is a 20MM diameter, loft set at about 45mm, total height 105mm.
I'm not sure if you all make measurements when setting or not, I was winging it. Have used it about 6 times. Nice cross between soft scritchy with plenty of backbone. Seems to prefer soaps, but works well with creams as well.
1965 SS, Slant, GEM Jr., G-Bar, PAL Adjustable, Schicks, Red Tip, SA, Slim