So I got my 120mm Zeiss Jena in a neat package wrapped in twine from the Czech republic. It looks to be in good shape and mounted easily to the 5D with an inexpensive adapter.
Last weekend I took it out on a shoot and used it for the interview with a photographer.
Really happy with how it looks. The next step would be to put it up against a comparable modern lens to see how different it really is. It still has the limitations of a still lens for filming motion like clicked stops and and the focus rotation. I’m already looking at others that would be a good match. maybe a 65mm? An 80mm for sure.