you can retrofit a tyre inflator instead of the original compressor with some small addaptions to the initial "hardware" , or measure the brushes and get something close then file them untill they fit, here you have various brushes(see the long list below)
20 Pcs 999021 Electric Motor Spring Carbon Brushes 1/5" x 1/5" x 29/64": Amazon.co.uk: DIY & Tools ... IMO dont ruin a well enhanced D2 just to make it cheaper to fix... sell it to somebody who likes it as it is and can afford to keep it then buy a D1 if you want coils and harsh cornerings...the SLS really makes the difference..just think to off-road mode, extended mode, self levelling when towing...etc ... a friend of mine fitted that Britpart sh*t and it lasted around 5000Km before one spring became shorter than the other`...and the car dragged it's back on the road with the caravan attached