In relation to Gwen’s specific question about the Kowa adapters, I can only repeat that I tried the 14 and the 21 Pentax XW and they did not come to full infinity focus. With the short(grub screw) adapter the eyepieces did not fully seat but rested on the glass plate.
Jerry .... after thinking more about your quote I slipped the Kowa Astro adapter the one with the short grub screws over the Pentax XW20 eyepiece just to see how much of the eyepiece barrel was left sticking out past the end of the adapter and it made me think about the time I had shorten the length of a Pentax XW20 1.25 barrel length by simply using a small hand held copper plumbing tube cutter. It’s simple/quick with a accurate clean cut. There is a few millimeters that can be cut off the end of the XW eyepiece 1.25” barrel before one touches the inside retaining ring for the next inside lens element. I do not remember any of the eyepiece port depths on either of the 77 or 88 Kowa’s , but maybe just this simple shortening of the eyepiece barrel which by the way does not effect its use again in any other scope port other than removing the eyepiece ability to have a Barlow lens attached. Doing this maybe it would allow the Kowa eyepiece with the adapter to seat flush and come to focus .