Thanks, guys. The probability of going the Z route is now 99.99%. At some time I just have to come to grips with the Z system as a work horse and this opportunity is as good as any. I know my beloved Df inside out and now need to learn the Z in the same manner.
I'll be centred on the Z6 with 50/1.8S and the Fotodiox extension plus FTZ. Additional lenses 8-15 Fish (vis + IR), 24/1.8, 60/2.8 Micro, UV-Nikkor 105/4.5, and Voigtländer 180/4. The three latter lenses to be used on my full-spectrum D600. There will also be a filter heap of some size for 52mm thread.
In addition to the above, a small field kit of AW1 + 11.5-27.5 (for Sky lochs) and possibly the V1 with 18.5/.8.
A cut-down Sachtler tripod and Burzynski head round off the gear list this time.