When I bought my fly screen (2nd hand) it came with the mounting brackets, but not the parts that mount it to the forks.
I wasn't that keen on those stock mounts anyway, and didn't really like the way that the screen looked in that position, so I made up my own mounts.
I wanted the nose of the screen flush with the head lights.
And yes it is just fine at any speed that I've cared to travel at.