Why I asked for people in the know is because my 60mm lens does cover the full 6x6 negative and it seems to be quite evenly illuminated, too. But I'll do some tests and update.
The Focomat manual and Leica product catalogs I looked at do not indicate if the 60mm is a wide angle or not. So, perhaps it is. Best way to check is with a big enlargement. That will stress the coverage at the corners.