Need help from Audio/Audacity expert

[Invader_X]

Hi guys,

I need some help.

I've been wanting to replace the battle track to this: https://www.youtube.com/watch?v=rKGbZYRUv28

But starting at the Remastered version and getting it to smoothly transition from non battle to battle encounter.

Problem I am having is that a bit of the original sound track spills over and it doe snot sound good. Second problem is getting it to loop.

I was wondering if anyone could please help?

I have the MP3 file here if needed.

Much appreciate!!