The setup to machine the angle on the jaws turned out to be a PITA. In the end I settled for a vice in a vice arrangement that was slow to set up but at least reasonably consistent. So, after roughly levelling the tops of the jaws, I cut the angle ... twice 'cos first time I didn't take enought off to leave a nice small point to the jaw.
Once the angles were cut, I just needed to trim off an extra tooth of a couple of the jaws , machine a Cartouche for the jaws number and remount in the chuck for boring and facing.
I now need to mount the chuck on a better backplate (with a set-tru adjustment) , then I'll face the chuck and probably the jaws again. .
I have as yet to decide whether to cut them to a traditional inside stepped form or maybe even cut them down and screw demountable jaws on the top ... It can wait 'till later.