That's correct. The drop is smaller because it's deeper where the sump isn't by a couple inches. The fords had to clear the crossmember so the pan hugged the block more. I can take all the measurements one would want from either front or rear pan. They look slightly different, but that's just me with a quick glance.
Barring the oil pickup location, would one be able to flip the pan front or rear? IDK if the bolt holes are symetric or if the front and rear main cover humps are the same size/shape.
IDK the oil capacity of the IH engines, if they differ or not from the ford ones. The bus's dipstick was aftermarket that was marked with an electric scribe by someone before me. First oil change I filled it with 11 quarts w/ fl1995 filter and remarked it with a cold chisel which put it at the center of the prior mark. BTW, both engines have the dipstick in different location. I had posted this at one time(here or on FB), but can't find it.