I'm sorry I can't point you to some literature, but you could have a look at the FTDI chip datasheet and and MIDI specifications.
I've used Motorolas 4N28 an 4N35, the white ones and it works.
Did you try the schematic I did post here?
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1187962258/60#71
The one in the first post seems to work only for the poster, many people have the same problem: No 100k & GND connection on 4N28 pin 1!