Peter Hill
I did one years ago when they first came out, using coach wheels, transferring the Hornby gears to the coach wheel axles. I also managed to prize the plastic brake discs from the Hornby wheels and re use on the conversion wheels, think I may have thinned them fractionally by rubbing the backs on a file.
If I remember correctly, the wheels were the blackened brass Romford/Jackson ones.
Pete Hill