Okay, honda's engine is less complicated and a LOT more reliable.The s85 would respond to boost extremely well, even in totally stock form. High reving high volumetric efficiency motors can get some amazing numbers. There are tons of 500-600whp Hondas running around with completely stock engines. A "street" turbo kit on a Honda S2000 makes 400whp easily on pump gas at low boost.
But yeah, the space. I'm sure with some cutting, welding, and work, you could make it work. If I wasn't afraid to cut the hell out of my car and had an extra M5 worth of money burning a hole in my pocket I'd turbo my M5 in a heartbeat!
Turbo S85 V10 in that upside down country, sounds amazing!