The shoes and springs I got from Nitro Models of Earby. The shoes were £15 and the springs were £2. The delivery was £3 and took two days from ordering til I got em this morning.
As for the engine, I got myself an RB TM728 for the Savage, leaving the S25 rattling around doing nowt.
http://www.nitro-models.co.uk Mugen bits here.