maybe I'm misunderstanding something here, but standard midi does send various sorts of messages, incl text, and possibly other things, and does not merely send '0-127' as you suggest. I wonder if you could show an example of the sort of message you're needing to send.
Otherwise, you might check up on the various Meta Event formats such as 01 Text, 02 Copyright, 03 Seq/Track Name, 05 Lyric, 06 Marker, etc. I have seen a case where one of these incl a Marker text and then data/codes for doing something other than the usual function - I wonder if this was something to do with non-Roman text characters? If it is a Meta Event that is rarely used, then this would be perfectly OK, it would also help if the data was printable even if it does not make any sense!