Do you not think your 03 has the .600? Mine did.
BDM can probably tell you if you send them your VIN. I know some 03's came with the .600 and some had a different cam in them. Don't know why they used different ones though.
sent all my info to both BDM and S&S and they both told me it COULD have the 600 or the 520 but for sure has the 640 springs as they installed them in ALL 107 motors.
Luckily, a fellow devildog sent me his 600 cam just in case.:flag: