Thanks for the reply Tazza, to get by through this job I made a pin out of an old kingpin I found in one of my “valuables” piles, (can't actually throw these things out you know).
I might be wrong, but the way I understood them, you could “progressively” tighten them as they wear in to the bosses, thus saving the need for any maching work. Sounds kind of like snake oil to me, but I think the bosses in mine are within their specs. and if I can save myself a pile of extra work I'm going to try it as long as the price is somewhat reasonable. After all, someone has to be a Guinea pig in these situations. I'll report back as it goes or if it doesn't, why it didn't.