My brother suggested a local company that may be able to machine a metal base for me. I rang them and they gave me the number of a bloke that may be able to do it for me. I rang him and he put me onto a friend of his who could do it. Sigh. In the end, I've found a man that can machine the perfect metal base for me for $100.
Well, it sounds like it will be perfect.
I pick it up later in the week, perhaps even tomorrow. Will post photos when it arrives, of course.