Milling down the engine cases is a fairly big project. Some people cut the swingarm itself, but if you do, you'll need to add frame supports to the outside of the swingarm axle. When I've milled the cases, I punch out all the swingarm bearings & grind the inner lip off soo that I can still install 2 per side.
The upper shock tower isn't that hard & is totally hidden, so if it doesn't come out as a thing of beauty, it doesn't matter. You'll also need a custom exhaust & this can be as big of a project as you make it.
If you need to be walked thru any of it, I'd be more than happy to help. You can reach me at: motomaxy@yahoo.com