Mancini mag mounts in 1970 Duster

Hi everyone,

I’m about to throw my 416 stroker back in my duster after the crank and Windage tray decided to become one.

I picked up mag mounts to replace what I think are just stock mounts and likely beyond their lifespan.

only one of the mounts has the counter sunk screw. Which side does it go on? They came with no instructions, website is just as vague. I did try calling but I was on hold and had plans so I had to give up on that.