For what purpose? In other words does it have to meet some racing body regulations? If you just want a shut off, consider buying / building a remot setup so you don't have to run heavy cables all over
I used a Cole Hersee 24213 solenoid. It's activated with a small toggle switch that just turns the ground side of the solenoid on/off. Keeps wiring/hardware under the dash small and simple.
Wish4hemi any pics? Seems like a good set up I just googled it. If I’m looking correctly I can use this to interrupt my main power wire the two bigger terminals on solenoid. Ground the one small terminal and run a hot off my battery to a dash switch and then to the last small terminal?
I almost suggested a solenoid, but remember---whenever the thing is on---it draws current!!!! IF you don't turn the battery off every time you park, it will drain the battery (eventually)