I would recommend against limiting your players to “classes”, it goes against a lot of what makes Open Legend special, as well as requiring a lot of work on your behalf to try and work out how to separate all the Banes and Boons.
The easiest way to do a particular setting in OL:
- Explain the setting to your players
- Be there during character creation
- You don’t need a step 3
Have your players decide how to build their characters, and make yourself available to answer questions about what works and what doesn’t work for a character idea. Have them come up with explanations for how they came by their abilities rather than just handing then a set explanation. It’s far easier to just use the existing system, and you’ll never end up with a character that doesn’t fit the setting because you can just say “this character doesn’t quite fit, how about we change it a bit?”
Give it a go, you’ll be surprised at how well it works. Best of luck!