Sorry Alan but anything you do find will be unreliable in practice init?
I do sympathize and fully agree that there should be a reliable source of correct measurements but in the making tolerances differ so much between manufacturers it makes it impossible to facilitate.
I overcome the situation by turning between centres which in effect are cones by their nature or making my own bushes to fit, I believe many others do the same.
A rod of Delrin or Nylon is cheap and easily turned on your existing lathe with the tools you already have and makes wonderful disposable bushes.
