I don't know if they ship overseas, but an Oz shop specializes in the M117 for track work, since they race a pretty mental 500SL themselves...
https://dkubus.com/?product_cat=race-engine-parts

A bloke in the local clubs circuit I know put a pair of these race cams in his 500SEC, with a quad exhaust and a piggy back Franken-CIS/E kit and it's a pretty hot street car. He's probably pushing somewhere around 300hp.