Why not just get the right stuff? If you must use the FA, I don't think it would be an issue. The difference between Dex and Type F were friction properties in the fluid specifically for the clutch/band material in an auto trans. In the case of a NP208, you are only using the fluid to lubricate bearings, chain and gears. I would use it in a pinch if I had to, or had an abundance of Type F laying around.
I'm not one to comment on the quantity. I filled mine with 4+ qts and have yet to have a problem. Others say if you put more than 4 pints in it will expell from the vent tube. My vent tube is clean and clear and have yet to see any fluid come out, even after driving to work and back in 4hi during some snowy days.