First things first . WELCOME, Nico. We qre glad to have you.
The engine number should have one more digit, probably before the 3. It does appear to be a 320 CI engine. I believe it is a 1937. 1937 numbers began with 3,176,225 for the big [320] series. Perhaps clean the number pad and take a picture of the numbers. The one circled in red. The number should be under the water pump as well, with only the seven digits, as you have here.
Ben