The current model has the black head and muffler. Prior models were natural finish.
Break in is normally done at wide open throttle and you limit the RPM to 5000 by making the high speed so rich it will not run faster. That keeps it cool and lubricated as the ring and cylinder break in.
I'd make sure the LSN is not completely closed, maybe one or two turns from closed. Then I'd open the HSN needle even more than the manual calls for on initial startup to be sure max RPM is not too high, and adjust from there.
If you're not comfortable with that: Great Planes / Hobbico is now the distributor of Thunder Tiger so you can probably call Hobby Services to get a starting point for the LSN.
http://www.ttamerica.com/techsupport.html
Telephone: 1-217-398-8970. Available Monday-Friday, 8am-5pm U.S. Central Time.