Since I noticed that you can upload soundtracks that are rare to find, how about uploading the two Metal Slug original soundtrack albums by Noise Factory? Specifically, the Metal Slug 3 and 5 ones. I found uploads of them on other sites but most of them are either on MP3 VBR V2 version or have no FLAC version at all. That is concerning to me as I'm more of a VBR V0, 320kbps and FLAC guy.
In fact, according to a certain review on the VGMO site, the reviewer mentions that he recommends the original Noise Factory versions for the Metal Slug 3 & 5 soundtracks instead of the ones found on the Complete Sound Box due to sound quality. Also, they are out of print and Noise Factory has already been defunct. Here are the links below to prove their existence.
Metal Slug 3 - Original Soundtrack: https://vgmdb.net/album/654
Metal Slug 5 - Original Soundtrack: https://vgmdb.net/album/657
If possible, upload them in either MP3 (320kbps, VBR V0 or both) and/or FLAC. In my opinion, this request is entirely optional. I can understand if you decide not to fulfill it as I don't mind it. That is all for my request.