19coronet50

I used an equalizer with a Bluetooth add on. I put a speaker on both sides of kick panel and a small amp in the trunk. Il add photos when the sun comes up

I have the 230 with gyromatic transmission. The previous owner swapped the carb for one out of a 53 gmc. And it was converted to 12 volt negative. My question is how do I install a kick down switch. The only way I go down to “low” is by coming to a complete stop.