I have a 67 convertible, it had a super turbine 300 in it. on the side was a purple wire that plugged into the transmission. everything I have found says it's a kick down wire, so where does it go top side?

It should go to a connector that attaches to a kickdown switch mounted at the carburetor. The connector at the carburetor is 2 wire. The switch gets power from the wiper motor connector on 68's, not sure if it's the same on the 67's though.

Thanks, I'll just half to trace it up as the kick down switch is long gone.

The parts you need for the carb connection are easily found online. If properly installed you should see a dramatic improvement in performance. The attached shows a TB400 switch assembly. Not sure it will work with your tranny, but what you need is out there for sure.