I am trying to figure this same thing out on my '26 roadster. I have '28 and '29 bell housings that have pedals on them. They are probably the same as your '31. I haven't really looked closely yet but I'd like to mount the old pedals on a bell housing that will bolt to my 153 and Saginaw 4 speed.

"I wonder if God created man because he was disappointed in the monkey?" Mark Twain