I am surprised that you have not had any replies to this, Kriss.
I have never done it myself, but one thing that springs to mind is the gearbox and gearchange mechanism.
The VVC engine is mated to a Rover/Honda PG1 gearbox, while the 45 will have the Rover/Peugeot R65 gearbox.
Even if the R65 can be mated to the VVC engine and flywheel, I am not sure if it could handle the power/torque of that engine.
So assuming you will end up needing to use the PG1 gearbox from the MGF, you will need a compatible gearchange mechanism and driveshafts from a 1.8 petrol or 2.0 diesel Rover 45.
The MGF has electric power steering, so you will need to transfer all of the power steering pump and pipework over from the old 1.4 engine. Possibly aircon too?
I would think you would also have some wiring to sort out.
Good luck with the project and let us know how you get on
