Hi Rich,
As Chris says, I had a very small batch of these brackets (part #108466) made up several years ago.
As I saw it, there were issues with all of the replacement brackets on offer from the vendors at the time. Some of them didn't have the correct bend / profile and others were constructed by welding a nut directly onto the bracket which doesn't give you any adjustment when fitting the set screws. I also felt that this wasn't particularly great from a serviceability point of view. With the original factory style nut assembly (part #SP10158), if you snap a screw then you can just pop the whole nut assembly out of the bracket, chuck it away and fit another one. Probably not such an easy fix on the brackets which have the nut welded on.
I had a press tool made to produce the brackets in stainless, replicating the original curve of the factory brackets. The only aspect which differed from the original design was the little strengthening "bump" on the bracket. Replicating that would have made the whole project unviable from a cost point of view. I noticed that none of the other replacement brackets available at the time had that little strengthening bump either, presumably also due to the manufacturing cost.
The nut assembly I used is fully stainless too, manufactured in the UK, and has the correct dimensions on the "legs" to fit the brackets snugly but still provide movement for adjustment. I've still got some of these stainless nut assemblies so just drop me a PM or an email if you need any of those. I can do a full car set of 5 for £4.50 inc. postage within mainland UK.
As it happens, after all that I ended up refurbing the factory brackets on my car in an effort to keep everything original but I sold all the sets I had made to various owners who were restoring cars at the time. I think one or two sets may have gone overseas from memory too. I still have the tooling so I could probably make another batch if there was enough interest. The tooling cost had to be recouped on that first batch so they would be cheaper second time around. I haven't checked though, there may be better versions available from the usual sources these days.
Cheers,
Phil