Ok, let's refocus this discussion ...
1) The lens is a near-symmetrical double Gauss lens with eight elements in six groups.
2) The external menisci were set with the concave side pointing outward, but that may have been the result of storage (to avoid protruding lens surfaces being scratched accidentally)
3) The lens mount has large perforations either for cooling or heating of the lens assembly
4) The lens mount as found is in itself complete and has no (space for a) diaphragm.
5) The centre of the lens mount (on the smaller side) has an external thread, which suggests that a cover/cone could have been screwed on here. A narrow groove would provide a light tight end to this
This may suggest that the part that protruded from the unit was the section with the smaller diameter, rather than the section with the wider one. That interpretation is supported by the orientation of the fasting screws on the lens mount.
6) There are no markings except for numbers on the metal fittings.
The lens glass is unnumbered
7) The reconstructed focal length of the unit is about 31-inches with an aperture of f6.3
8) The 'viable' interpretations are
a) an aerial camera lens
b) a lens from a projection system
What's now needed is to first find a positive ID of the lens pattern:
and then once that is clear, work out where the lens came from.