That item would be the water pump or are you speaking of the oil pan orientation?
The radiator hoses are about the only thing that is correctly oriented.
The alternator,starter,exhaust ,power steering,aircon and a few other things are all on opposite sides,or they were when I swapped my 3F for a 1HZ in my 73 series.
Its not hard,but its not straight forward.
You also need the gearbox to suit the engine due to the spline count,or swap the input shafts
T/cases are interchangable,but if you have a choice,use the one with the 38 mm idler which is the latest design.
You would need to swap the tacho as the 1HZ and the 3F recognise different signals and the 1HZ gets its signal from the fuel pump ,while the 3F gets it from the alternator.
Oil pan wont be a problem as long as your 3F is from a landcruisEr and not a Coaster bus,forklift or something