Leitz Summar on an enlarger
This may not work as well as you think. The Summar was designed for use as a taking lens and using it in such a short range on an enlarger will introduce all sorts of aberrations. Camera lenses CAN be used for printing quite successfully but they should be reversed so that the front element faces the film. The same principal that suggests that a reversed camera lens on a camera body will give very good macro images. They still make adapters for this purpose.
I found this out when I tried to use a Pentax F2 Takumar on an enlarger with a 42mm adapter lens panel, the centre was sharp but the fall off was dreadful. Get the edges sharp and the rest was out of focus.
Yes the Summar was not a bad lens considering when it was made. Stopped down it could produce some fine results. I would like to see the one that had been coated, (Mentioned a while back in this thread)