Great advice from William!
The other thing to look out for is the bushing rod which can be bought in different diameters and has a hole through it. This can come in very useful as it can be cut to size so when you do come across that odd bush size you can cover it.
http://www.hswalsh.com/product/bergeon-bushing-wire-500mm-cw212 just to give you an idea, comes in various sizes.
You just cut it to the size you need