Hello,
I'll be happy to make the edits for you, you won't know where it's been done!
It's a 1 day job, you can have it ready tomorrow if you send me the songs/links today.
I'll even out the levels if needed so it all sounds great together. I might make some kind of a transition if it fits - crossfade, reverse reverberated fade in, or whatever would sound good.
My background - I work with audio every day, editing voice or instrument recordings, which is much more difficult than what you need done. (Well, also a degree in music, but no one seems to care here)
Best,
Vladimir