you can use the 200 disco airbox and fit the box just in front of the heater box...
i can also see in your pic that the pipe from the cyclone breather has been cut and its just hanging there. that bit is connected to the airbox too..
When i bought mine it also had a conic filter ....
so i got a disco 200 tdi air filter box...
this is mine below....
as you can see the hose to the left goes straight to the turbo, and the little bit of plastic sitcking out, that's where you connect the pipe from the cyclone breather, which on yours is just loose...
the other end goes to the snorkel/air intake
dont have a better picture at the mo, so this one has to do (when I was working on the heater box)
as you can see, my air filter box is just there behind the rad.
one hose goes from the bottom of the box straight to the turbo and the other one goes next to the alternator and then to the back, and to the side air intake
I couldnt fit it in front of the heater box as I have the screen wash bottle there, but on yours you have loads of space to fit it there.