Since the 4 cyl block is shorter than the 6 cyl original, I'm sure the axle won't be a problem. Thy to keep the bellhousing in the same relative position.
I was hoping to be able to set the block down between the frame rails so that the top of the taller diesel block wouldn't stick any higher into the cab. Without drawings, I don't know. Based on the old 4/6 BT dimensions it would have to be set back quite a ways before the taper of the frame would be wide enough to clear. That would put it so far back the engine would be partially under the seat. That would not be good.
Wish I could find drawings of the international ISF 2.8 or 3.8 engines as I think that is the family of the R2.8
