Yeah Rob. now I've got two dials, just finished the second one over the weekend.
I've found some nuts on ebay for 12 quid each, which is probs less than the material and tooling cost. The threads look like ACME its hard to tell but yes you could be right, it would be a worthwhile project. I'm busy making an adjustable carriage stop at the minute, then will come the splash back but I could do the screws as a future job.