It seems you're following the Krebs setup
At
http://www.krebsmicro.com/ You have the relevant info about this eyepieces, and because you have the scarce NFK 1.67X this one would be the best option to match the field of view of your microscope with these cameras.
If the color correction of the NFK is adequate for your Leitz objectives (I found with my only NKK 3.3X that it's very close, but the field of view was too much reduced and optical aberrations increase to the periphery) it would be easy!
One issue with this kind of setup would be the dust entering to the sensor, a major problem in photomicrography.
I use Leitz objectives in a Zeiss scope and my solution is a Periplan 6.3X and a Zeiss 63mm 0.25X camera adapter (total magnification 1.575X on sensor)