Choosing either end song will always be a big annoying controversy, I suggest a "neutral" choice. There are many familiar Star Wars themes that would work well for the end, Leia's theme, Luke/Leia's theme, the extended throne room, something everybody already knows and likes?
About Boba Fett's death, maybe its possible to "steal" the later shot of Han throwing the bag at the officer in the bunker, (the guy whos says "freeze") and alter it to be Han deliberately swinging the pole at Boba Fett. In other words we need three shots to kill Fett on purpose:
1. Han's blurry POV of Fett preparing to fire at Luke (that shot is there, it just needs to be made blurry to imply it's Han's POV)
2.Han "attacks" using the aforementioned shot, it would need to be flipped, Han's vest erased, and the background changed to desert. The bag needs to be altered to be the pole that Han jabs with (it sounds impractical but that recut of Superman 2 on youtube has similar stuff)
3.Fett's backpack is struck, but with Han cropped out so you can't see he was facing the other way.
Maybe the subsequent shots of Fett flying through the air, his legs could be on fire from the burning jet fuel. He hits the barge raining flames.