I LOVE that mount you have for the Lee press. Do you have plans that you can post or send?
Right now I just have my Lee Pro 1000 mounted to a piece of 2X6 that I chuck up in my ww'ing vise. It's stable enough that it doesn't move when I crank the handle (the bench is 2X6 framing with a 10/4 oak top), but pretty it's not, and I'm not sure how I'm going to get the spent primers out short of unbolting the press.
All the best,