Am I wiring this correctly? (safely) - race car wiring

So I have been preparing the rx7 for stage rally and part of this is wiring/adding circuits/etc.

Part of this is a more safe master cutoff switch, not required by the rules but above and beyond reqs/feels like a good idea.

Right now I have my ignition wired on a toggle that operates the ground of the ignition relay.

but with the proper cutoff switch (also on clearance at summit.GFORCE P# 3101 for 11 bucks!!!) I want to be able to kill the ECU/battery/ignition all with one clean switch.

Here is how I have the ignition now:

Here is the schematic:

Here is my proposal to add the wire:

...am I interpreting this right?

https://www.summitracing.com/parts/gfr-3101/overview/

is your orange thing the starter? is the thing marked 'z' the cutoff switch?

I think I see what you are doing but if the answer to the above 2 questions is 'yes' then I think the cutoff switch will only cutoff the starter.

If you only disconnect the battery but not the alternator I don't see how this is much of a shut off switch. More of an anti-start switch. Maybe I am misunderstanding your sketches.

The Z terminals look like they are to de-energize your ignition system, the W terminals look like they are for the alternator and the main terminals open the battery cable.

All the power for the ecu and ignition an everything comes from the smallish black wire coming from the 80 amp fise under the hood.

Interupt that and it kills everything.