I don't specifically see Dalmac, though perhaps one of these has similar optics. This website is in French, though it should be simple enough to follow the links.
The Dallmeyer Dalmac 9"/3.5 as descibed in the Vade Mecum is a Q15 or a Tessar design. Should cover 5x7 but not much more. They were made in several focal length from the mid 1920's to the mid 1930's
It is a pretty large piece of glass so i would think that a #5 shutter is needed if you want to keep the 3.5 apperture setting.
You can get more information about the exact shutter specification for your lens from: http://lensn2shutter.com/shutters.html
Good luck with your Dallmeyer