The kickdown is a cable from carb to tranny. It is not necessary to hook up. It downshifts for passing. If you have electrical wires with a connector that connects to tranny, you may have a lock up style 350 or you may not. You need to examine the transmission to find a connector. (drivers side, half way, 4 pin) Study the web for where it's located. They are on later 350's. It will need to be hooked up. You will have to give us better info on what you see. I don't believe a 350 has a built in neutral safety switch. There should be a stand alone "mechanical" switch operated by column or floor shift. The movement of the shifter operates it and the backup lights. I assume you have a aftermarket floor shifter???? If there are no connectors coming out of tranny, then the wires are for neutral/backup. Prevents starter from working unless in park. Backup lights are wired to come on when lever is in R. Could be one switch does both.
If you have a cable from carb to a tiny tranny rod down in a hole and you want to hook it up (kickdown), see web for instructions. No wires for this. Again, it is not necessary. You can down shift by hand, but do you really do a lot of "power passing"?

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