Poptop, I am not re-profiling the S8 tip.......hardened steel is tough fro me to cut using my woodturning oriented gear *(This is usually the point where Kyle, Rob and Alan make fun of me 'cause I don't have/use a precision lathe).
What I do is to turn down the tip section of the BK so that the OD of the top body at the tip is the same diameter as the base of the S8 tip. This creates an issue with the bottom bearing well which is now to shallow and the bearing protrudes out slightly. So, I deepen the bearing well so that the bearing again fits flush. Also, and quite important, with this mod you have to make your own spacer for between the bearings,
and, you must make an additional spacer for above the inside bearing because the tip shaft's threads don't go down far enough to lock everything in position.
As to the washer, it's a 1 1/4" ID x 1 7/8" OD machine bushing (14 gauge thickness). However, the OD is slightly too wide to fit into the BK body, so I chuck it up and remove a few thousandths from the OD till the washer can press fit into the top body. These washers are great for this application; they add 14 grams in weight which brings a BK up to the weight of a Guilia !
Any other questions?