I don't own a TN D700 but it is a supported radio. The cable driver
if the cable uses a PL2303 chip, is the same version as Windows 7 (3.2.0.0)
I supposed any driver will work for FTDI based cables. Knowing all this,
you can be 99% certain your radio, Chirp will work in Windows 8.x
and it works in Windows 7.

You can get the daily latest build of Chirp from here
http://trac.chirp.danplanet.com/chirp_daily/LATEST/

If it works with the daily build then you can just continue
to use that build. I don't install every daily build that's advertised.
Unless some new features have been added involving my radios.