single wire ignition bypass connector?

[threearmsinjune]

WHAT IS THE FUNCTION OF THE SINGLE WIRE IGNITION BYPASS? WHAT IS ITS PURPOSE? I replaced the intake manifold on my '89 350 tbi truck today. I updated to an edelbrock performer. while I was double checking all of my connections I found a male spade connector in the harness behind the distributor plugs. The haynes manual makes a picture reference to it as the ignition bypass connector but never states its function. There is a separate single wire that is disconnected when setting the timing. Does anyone know the function of this connection? There is also a bank of vacuum connections on the right side of the engine. There EGR and the MAP both connect here, there is an open port- is this to keep a reference to atmospheric psi or am I missing something? All seems to be in place but I want to make sure before I fire it up in the morning. Thanks for any input I know it isn't much info........
Chris