I just came across this flat tracker on bike exif. It is a moderately modified Ducati Scrambler 800, with a rather loud paint job, possibly inspired by the Britten V1000. It definitely makes me think that a street tracker build on a Scrambler 800 should be very easy to do. Engine wise, the Scrambler should be more than peppy enough with 73 hp and just over 400 lbs with a full fuel tank in stock condition.