I've always thought Deep Purple's Sweet Child in time was a difficult vocal, seeing as Ian himself can't really do it anymore. I was looking at some Youtube covers and found a few with the vocal chops,
Germany's Roxxbusters does a decent job on the vocals (only)
although poorly recorded

and Belarus's Petr Elfimov hits all the notes in this (over orchestrated) version.

but this kid bangs out the best rendition of just the first part IMHO,

a semitone higher than Ian, and he's mainly a guitarist, covers Yngwie tunes etc.