I was going to get them and then spend the time whilst they wing their way from the US looking at ways to do it :-)
a man after my own heart :)

I might buy a 50mm dia offcut of Ali and have a tinker on the lathe at work, will check to see if we have any boring tools to play with!
thats more like it :) if you over size the bore just slap a bit of epoxy in there it should easily take the cutting force (just dont use your posh bearings on that one lol