advice on air filters for 2.5 petrol defender

Hello

I have a 2.5 petrol 110 defender in need of a complete air filter kit,
at the moment there is a small plug in straight from the carb and it anit big enough,
some one has told me the part rc 4002 is what i need, am at the the moment struggleing to get hold of one, can some one out there help please !
the car is left hand drive dont no if that makes a difference,

plus any one with any advice on this type engine is appreciated.

thanks for reading