I love the cossie lump and all the nostalgia that goes with it but would also consider other options such as Duratec or even go for a full Mistsubishi Evo setup as per the 205 that Dimma recently built as they have much stronger 4x4 set up and are far more plentiful.

You can get 300bhp out of a Duratec quite cheaply under normal aspiration.