The first 10 years of Fordson, the Std bore was 4.000 inches.
Beginning in about 1929, the Fordson had a slightly larger bore, 4.125.
In 1938 it got a higher compression head. The result was that the bearings were over-stressed and the engine suffered reliability.
So the conclusion is, the stock Fordson is barely adequate.
By 1945, they were getting 27 hp out of it.
To go non-stock takes money: hardened, counterbalanced crank, bearing inserts, pressurized lubrication, stronger rods.
People are doing it with Model T or Model A engines.