The best of the port is there, but it's still got a few issues that could be fixed up before being accepted.
First, the mixing is off. Namely, the strings should be louder than the percussion, but it seems to be the opposite here, while the bass could be a tiny bit louder.
Second, there are some sections missing. For example, the cymbals after the intro of the song, or one layer of the piano notes. In the latter case, while I understand that you had to sacrifice it because of the 8-channel limitation, it's a prominent section of the song, so it sounds noticeably off when it's missing, so I'd suggest sacrificing something else if you have to. Alternatively, you could use chorded samples.
Third, the bass seems to be at an octave lower than it should be in certain areas, and it's possibly because of the sample you used; I'd look into that. As well, you put the bass on channel #6, so it will get cut out by sound effects; I'd suggest putting it somewhere else since it's a relatively important channel.
Fourth, @9 does not mesh well with the higher-quality samples here, partially because of how quick it cuts out, so it ends up sounding super empty, along with the missing chord notes. I'd suggest going fully sampled or fully unsampled here, but most likely the former since @9 is the only SMW sample.
Fifth, I'd double check your optimization; stuff like g+4r8g+8g+4r8g+8
can be condensed into the same loop, while loops like [g+4]3 take up more space since it's a single note looped too few times. (This isn't a comprehensive list.)
Sixth, you could call @9 more efficiently. You've already got it loaded it because of #optimized, but if you want the #default variant, then simply mix-and-match the samples you load. For example:
Just make sure that you put the file paths correctly. Keep in mind that ".." (without quotes) means "go up a folder". So if you have #path "Delfino Airstrip", then the optimized samples can be called as such: "../optimized/00 SMW @0.brr".
These are the biggest issues I noticed. Keep at it and this could become a stellar port!