Do you know if the plow you have is an Allis one or one made by WIARD Plow Co.? The reason I ask is the 2-way plows I have for my '42 B are WIARD and not Allis. They mount entirely differently. If you have an Allis plow that was intended for the B it should look like the ones here, including that portion of the lifting mechanism shown attached behind the seat.
I don't know about the hyd cyl possibly being the same...both my belly mower and my plows are manual hand lift. However, if you have the mechanism shown for the Allis plows, I can help you out with a diagram of how everything hooks up, including the hyd cyl for the non-manual lift. Let me know.