Unless I wanted to modify the seat even more, the catch would have to extend beyond the edge of the seat riser on the floor. I laid out a couple of brackets, cut them out and formed them. The brackets and catch were tacked in in case they need to be moved later. So far so good.
When the floor brace was cut to allow for seat belt installation, it left the brace a little flimsy. I cut four end caps and welded them in. They stiffened the brace up considerably. I may still add a piece of angle to bridge the three sections together.