That is a good way to use a smaller steady on a larger lathe without making it unusable on the original lathe. You do really need a mill to make the adaptor. I modified and made adaptors for 2 fixed steadies to fit the museum's Smart & Brown model A simply because the original ones were costing £150 plus on ebay. Both were intended for Chinese lathes, the small one can handle up to 2" diameter and is C shaped and the other is up to 3 1/2" and hinged. They both had their bases cut off and were milled to fit Aluminium adaptors. They can both be bolted to either side of the adaptors which helps when setting them up. To make them easier to fit to the lathe bed, the locking block underneath has a captive nylock nut which helps turn it into position when tightening or removing. The bigger one has a second set of fingers I made with little sealed ball races which are very good. I got lucky when a travelling steady for the model A came up on ebay cheaply because it was unidentified.