I have done a Dapol GWR mogul for a customer. I used Gibson standard wheels on 2mm axles made by turning the pin points off standard wagon axles. The driving wheels were bushed with Branchlines 1/8″ to 2mm reducing bushes fixed with Loctite. You do need to add Loctite when pressing them on to the new axles and must use a suitable press such as GW models as you will only get one chance at this. This is because th Loctite will grab the axle so well that trying to use a wheel puller will wreck the wheels. The tender had gibson wheels fitted onto the original Dapol axles. Note that Gibson also makes similar bushes but I have found them eccentric! The loco was able to negotiate an A5 turnout and curves below 36″ radius even though there is not much side play possible.