Thanks for looking in, everyone!
The adjustment of the valve gear is likely to be tricky enough without having to dismantle everything to change the length of links. The use of different threads on each end is a new idea for me - thanks. In this case though I may need a couple of mm of adjustment.
On the original drawings the ends of the rod ends were left square across, but this looked a bit crude, so I rounded them off. This is one place where I think it is easier (and more satisfying) to use hand methods, the time taken to set up the rotary table etc. etc. just doesn't seem worth it.
David