After some careful consideration, I decided to make a few changes to the function of the push-button starter. These changes are intended to make starting the boat a more deliberate act and also to improve security.
So, you will only be able to start the boat when the ignition is ON, not from OFF or ACC.
Also, instead of a toggle cut-off switch, you will need to use the original key-switch as the cut-off switch.
These are minor changes, but I just wanted everyone to be aware of the changes since it is slightly different than I quoted before.