Thanks, gssixgun. I got the 22mm super silvertip from thegoldennib.
Although the website has it listed as 65mm in height, my digital calipers tell me its 68mm. The glue/polymer at the base of the knot is 8mm on one side and slopes up to 9mm on the other.
I currently have a 10mm-deep hole bored in my handle, but was planning on taking it down another 4mm to make a loft of 54 (68-14=54). Not dead set on this depth though...
-Dave