its hard sometimes doing a remix of an older source such as zelda or mario where the source you have to work with is under a minute or so. I did a remix of the dungeon theme myself, but mine was heavy/power metal influenced. Mine ended up coming out to 4:13 and i just recently subbed it a couple weeks ago.
I think the hardest part is taking the source and being able to manipulate it enough to where you can create a structured song (ie chorus, verse, breakdown, etc). I actually used the very short discovery theme and the whistle theme to kinda create a breakdown in mine cause i couldn't figure out a smoother way to transition into a guitar solo. Anyways, i think that as long as the song doesn't push 5 miniutes, you can keep it right at 6mb at 192kbps and it'll still sound very nice compared to a 320kbps file.
ALSO, Sweedrix, i've KINDA noticed that you gave up on adding the strings to the gerudo valley mix? You know i can always just keep the strings for the parts after the guitar solo cause those you really seemed to like. LET ME KNOW?