Unfortunately, I am not familiar with the Magnum wiring harness and, have nothing to put my hands on to help.
Your are not the first person to have this issue.
Someone knows the connections. Stay after it.
I’ve got it starting and shutting off with the key. It’s not 100% correct because I’m still using the original starter relay and not the one from the magnum fuse box. But it will work for now.
