Safety neutral switch
Heh!! The problem of course, is that I can't "see" what you have.
I assumed you are trying to (or have) eliminated the Mopar relay, and are using a Ford solenoid in place of the Mopar start relay
NOTHING wrong with that.
I assume your start button fires a relay in the 50001 relay box, the output of which fires the Ford solenoid
Nothing wrong with that.
The whole thing comes down to, I don't believe the BM swiches are particularly heavy duty. They MIGHT stand up to the Ford solenoid coil, but I'm not all that confident.
That's why I suggest breaking the line from your start button, and inserting the BM switch in series with that.
The relay in the 50001 box SURELY draws much less coil current than the Ford solenoid, so that should unload the BM switch.
Otherwise, if your start button is heavy enough (most are) you don't even NEED the relay in the 50001 box. You could just go power -- start button -- BM switch -- Ford relay
(By the way, if you need coil resistor bypass for start, the Ford relay makes that easy. Get the old style with FOUR terminals. The "S" terminal goes to your start button/ NSS circuit, and the "I" terminal is wired to the downstream side of the coil resistor.
I'm assuming from an earlier comment, that you are installing a jumper on the two existing starter connections, and running just one large ga. wire from the Ferd solenoid to the Mopar starter?