There are two different Zero themes, this is the "resolution" theme. I call it that because it followed chaos as calm. You should blend the "action" theme into it. The "action" theme is the one you hear as soon as the shot is fired from his Z-Buster and he rushes Vile.
I 'd say that if you blended both sequences, the first sequence with absolute hard metal and this sequence exactly the same it would make for quite the theme music.
If you follow my advice you'll have a lot of Zero fans following you. I can't get enough of the character, his mystique and the fact that he is a Maverick converted into a Hunter. (Oops, spoiler alert!)