I haven't tried the Old Brits steady but it looks expensive.
However I have home built the Captain Norton noted affaire http://www.captain.norton.clara.net/mtp.html
which uses two track rod ends and a few bits if angle iron and it works well.
I welded rather than epoxyed the angles together and used two short bolts screwed into the old rubber buffer holes instead of the flimsy through bolt.
I have one and it works as advertised. It is a high quality product, so it is not cheap. The installation was relatively easy, though I had a little trouble understanding the final adjustment, but a phone call to Fred will clear that up, as he is usually quite helpful. Having met Fred & Ella at the Lumby and Mt Adams rally's, I can say they are really nice people!