After buying my Kowa 883 I intended to buy a TSN-DA10 and start afresh with my old Nikon CP4500 but I never did for various reasons.
Instead I recently bought a Nikon D90 for general use. I use a 70-300 to give me at least some reach.
I've read about your exploits with the Pentax K20D and feel that this could be the way forward.
What kind of lens do you use on your Pentax? There is a 35mm f/1,8 Nikon I'm interested in for indoor shots and this has a 52mm thread. Maybe this could be used for the same combo that you have?