Wow, thats's some ABC, Joe. I can't figure out all of it, but 1/8 note is basis for 6/8 time, and you only have to note differences when note is not 1/8. 37/8 in your code is then 37/64 real time (fraction of measure) or a little over a half note.

Should be z/2 then for a sixteenth, and 2z for a quarter note, etc.