Sota/Koetsu Vermillion---what arm?

I am looking for guidance in the most bang of the buck, tone arm. Compatible with my Sota & Koetsu. I presently have a Sumiko F4, and would like to upgrade. Used ofcourse.
Most bank of the buck is a FR-64s (with intact bearings), that one was also my best match with my Koetsu Rosewood Signature Platinum. From the modern Arms the Graham Phantom was the best choice.
Looks like I am stuck with the Sumiko F4, with the Koetsu for now.Any opinions on how compatible this will be? Any comments or suggestions will be appreciated.
If it is any consolation, the Koetsu tonearm was made by Jelco, and I believe I'm correct in saying the Sumiko was, too. If that's the case, you could do a lot worse.
Have you considered a Micro Seiki MA-505? IIRC, it has the same spindle to pivot distance (222mm) but might take a slightly bigger armboard hole (28mm).