Hiho,
No clue other than to wait for one to come around. I know they made them
for after-sale because I saw a table in Japan years ago which came with
something like 5 extra headshells still in their boxes. I think the KP-07M
made by Micro is the only other 'Kenwood family' table with a straight arm
and SME-type headshell mount (and I am only going off what I t-h-i-n-k the
KP-07M headshell is having seen the arm a few times.
That said, you might try something else... there was a cheapo Denon table
made until 4-5yrs ago called the DP-300F. It had the same kind of headshell
I am pretty sure. Given there is a Japanese standard which defines the
headshell collar to stylus tip distance at exactly a certain distance, it will
probably work if you can get the offset angle right. Try googling "PCL-
310" or "Denon DP-300F headshell". The mounting distance
is a full inch shorter (Denon shorter) so the offset angle will probably be off,
but the Denon headshell has long slots to mount the cart so I bet you could
angle the cart out a couple of degrees to get it right. You could probably find
one cheap enough on fleapay to have a crack at it.
Harmon Kardon also made straight arms with removable headshells back in
the day, and perhaps others did too.
The other solution would be to put a different arm on, or just wait for the
Kenwood headshell (either for the KD-770D or the KP-07M) to come up on
fleapay.