I have the same type lens in one of those cameras which can take a roll film back (e.g. a Plaubel back which I have a couple of). Then then film will be more flat. It runs down to 1/25 sec. but needs a CLA if the slow shutter times has to be used. I think the lens deserves a flat film plane :-) .....I also have such a camera with an uncoated Heliar which I think I will try. It is a 5 lens design but I don't know how well corrected this lens is. But some describe its image potential to be magic :-)
An efke ISO 25 for 6x9 could be a good film for testing the resolution. Some years back I tested the Gigabitfilm (ISO 40) for 35mm cameras. A film with very high resolving power. But it never came out in roll film only as 4x5 sheets (ISO 25).
It is funny to play with these old cameras.