I have not seen any new replacements, just old units in good shape that are refurbished. I am pretty certain Tom Myer's truck parts in Miami ok(I do not have his number, It is a 39-55 Chevy Pickup salvage yard) would have some used brackets in good shape, You could also take your old ones to a local machine shop and have new brackets made- That is the only way I know of to get new plates.
Flipping them around so that the link is perpendicular is the way to go- that way the force rides on the bushings rather than side loaded on the bolt.