My QHA has the oil pressure switch and wiring for the kill switch- but no kill switch. All I had to do was plug the kill switch provided with the kit into the wires on the engine and it works fine...then replace the switch with a decent one from Radio shack because the proded switch is junk, but that's another topic.
That being said, I bought my engine almost a year ago and they could be slightly different now.
I am glad that we no know that both work- great! Not only are these engines available new, but they have been used in numerous pieces of equipment and it's great to know you can get a used one and have some level of confidence that it will work.