The circuit itself isn't mine although the artwork itself is as I drew these schematics up myself in Express PCB. The circuit came out of a Marshall JMP-1 valve MIDI preamp, and from what research I've found it appears to be a pretty standard hook up for the 6N138 optoisolator for MIDI In.
What I was hoping to do was have this thread made as a sticky for guys who were wondering how to properly implement a 6N138 optoisolator into a MIDI In circuit. The ones I was finding had pin 7 disconnected and a resistor from pin 8 to the positive rail. However, I had found others who tried that configuration who observed receive errors and such, only to find on a scope that the rising edge of the "1" bits all had a "curve" in them. Tying pin 8 straight to the + rail while installing a resistor to ground on pin 7 seemed to drop the rise time of the output transistor, which sharpened up the rising edge on the "1" bits, which cured the receive errors.