Hi!
It's just filing and sanding!
No problem in any way of modifying any prop as long as you know what you do.

1. Always file and sand on the front side Curved side) otherwise you might change the pitch .
2. Keep the blades as thin as possible.
3. Don't be afraid to do drastic modifications...how do think they made the prop in the first place???
4. Thin and long blades is better than short and thick.
5. Always balance your prop after you have modified it