I have the 10242 for my 5.9 Magnum, got it years ago. Might buy another reg B&M plate and cut notch out the same way.
It's made for both the 904 and 727 converters also.
Can you take a pic of it? Or make me a template of it and send it to me. So I can make one for my 360 magnum. I am having a hard time finding a SFI one for mine