I currently sell billet aluminum wheels (see link in my signature below) that are based off the stock wheel sizes - bearings too. When I say "based off stock sizes" I mean outside diameter, bearing ID, and bearing width. So they really are, a direct bolt-on. You will not have to modify anything.
Now, in regards to your hyfax wear .... The outside diameter of my wheels can be adjusted quite easily. Therefore, we can easily make the 5.125" diamter wheel a different size - like 5.25", 5.375", etc. We can make this same adjustment to the bigger 7" wheel as well.
So if you want to go this route, we can provide you with a replacement wheel that will be a direct bolt-on (no modding for different bearing sizes), help your hyfax wear, and look totally bitching all at the same time!!!