You won't find MANY links... you will probably find more about 325's with a turbo - and its the same engine.
http://www.turbo-kits.com/325_turbo_kits.html That's a pretty cheap kit, but keep in mind it's going to cost you about $2k more than what the kit alone costs - You'll need to tune the engine after the turbo is installed - and a new clutch. The stock clutch is good for about 210hp... I hope you would get more than 210 out of a turbo'd M50
Better than a turbo (sometimes...) is swapping another engine into the car - like that from the E36 M3. You won't be able to run much boost without forged internals on the M50. You should be good for a little bit of boost though becuase bmw overbuilds most parts in their engines, but if you could find the S50 from a 1995 M3, it should pretty much be bolt-up. But for $4000, if you have the time and knowledge of boosted engines (or a friend who does), go for it!!