Ninja Remix was actually written by Atari ST specialists Eclipse (Who also did some Thalion titles). An SPS (IPF) image doesnt exist because their decoder doesnt support Atari ST tracks yet.
Are all the versions you have tried the DefJam / Angels cracked version? The third disk of that set is a known bad dump / was always buggered. Is it easy to get to where the corruption takes place? Save game? Quick route?
I have the original but that is of little or no use to you unless I can make an Extended ADF.
This website has the HD version
http://lastninja.lemon64.com/dl_other.htm
It also has the DefJam / Angels version. Might be worth checking to see if that one is also corrupted and post back. Although I am sure it will be.
Because the Amiga and Atari ST versions of this game were written by the same people I would bet you that (apart from the quality of samples) they are almost identical.