Rack Hardware - Diving Board Plate Front - Taiwan
20-250 front/fork crown
Just as thick and strong and long and good as the made in Japan Nitto front diving boards; maybe even better since it's less expensive and includes a nut and bolts and washers that you may or may not need.
For mounting the Highrider, Mark's, Two-strut top rack, RBW-51 just in case your frame doesn't have rack braze-ons or in addition to the struts for redundancy. Some bending of the board may be required depending on the placement of your brake bridge, fork crown brake hole, size of your frame.