Hi! Would be glad to assist you on this project :) I have a Bachelor's degree in Music and have been writing and arranging music for years.
The problem is that I don't really get the task :))) I see the score for piano. So, why don't you just use the upper staves, where the melody actually is listed, and not to play it on your ocarina? :)
Would be glad to hear from you.
Kind regards,
Vlad