What do you mean by "sound anything like the midi"? Are tracks missing, does the soundbank instruments sound wrong? If it's the former, I can help if you give me more details. If it's the latter, there is no solution other than playing around with different instruments. The electric guitar has embedded distortion. As a rule, you don't REALLY need to follow what the label says. For example, a high pitched pick bass could emulate a harp.
I would suggest using an electric guitar to play your score. Other than that, you are experiencing the limitations of MIDI. Not that MIDI always sounds bad, but MS2 and the MLE program do not have updated soundbanks, making every instrument essentially sound like gassy shit coming out of a donkey's ass. The work around is to have a very keen ear for the selection of what music you might want to convert into MS2 in the first place.