There's usually about 10 different solutions to the same "problem" with a bike. The SBS appears to be the same thing as the Truvativ adapter, just more expensive.
http://www.amazon.com/Truvativ-00-64...o-euro+adapter

The quill to threadless adapters are a bit kludgy imho. You get the positives of a a removable face but still without the convenience of a true threadless setup. Personally, I'd just get a cheap threadless fork and buy the headset I posted. It costs a bit more, but you'll only do it once in the foreseeable future but the result is cleaner, lighter, and more convenient to adjust. That's just my personal opinion though.

Nice bike though! A good mix of retro and modern.