Complicated MIDI help request

[Marpy]

I have always loved Samuel Barber's Adagio, and would like a little bit of music based off of it.
What I want is kind of complicated, and beyond my abilities. Firstly, I want to add a 'hard' section to the song near the middle of it, where it suddenly goes upbeat with a hard rock/metal type sound to it with the classical instruments becoming a supplemental sound, before going back to the softer sound, where perhaps a single guitar remains throughout the rest of the song. And if it could be edited to loop a little better, that would be epic.
Edit: If it helps, it's the theme song of a character whose mother (who he was very close to) died when he was a child. Everyone thought it was just an accident, but later on this character discovers his own father was behind it, and his dad tries to kill him as well. Filled with rage, this character does everything within his power to get revenge against his father, and when he finally does, this character manages to find peace. I would like this song to reflect the grief, anger, and peace of this character's story. Thank you.

 

[Marpy]

Hello again, it's me bumping this. I did a little messing around with the original midi, and although I'm not very good, I managed to come up with this. This should cover the first part, I just need some one good with music to splice on a rock-ish section in the middle, with a nice battle music type sound to it. Perhaps something like RMVX's RTP Battle 5.midi. That's a nice battle theme. Only, you know. Angrier.

 

[Brewmeister]

I'm having a hard time determining where it 'suddenly goes upbeat'. How about giving us some times where you want to kick it up, and fade back out?

 

[Marpy]

Maybe it goes upbeat somewhere near 3:52, then return around 8:53 to the end.