You're at a +53 offset so they will be slightly sunken compared to a stock wheel. Running a slight spacer probably wouldn't hurt in this case. It may also be cheaper to get a set of custom spacers made that convert the hub bore down correctly. A place that specialized in custom spacers will probably be able to get the machining perfect as well.
I looked for a cheap and quick hubcentric ring adapter first that you could just slip on to fit but I had no luck.
The plus side of going the spacer route is that you won't be "damaging" the wheel and if you ever change your mind you will be able to sell them easier. I would be wary of buying a used wheel that has been machined. How much material can be safely taken off without compromising wheel strength? Especially material around the clamping area.
Also if you are going to have a shop do the machining, make sure they have very good equipment and experience since this is going to be an area that needs precision work. The tolerance should be very very exact if you want the wheel to fit well and not wobble or vibrate at speed. Definitely not an area to cheap out on.
Serpent autosport advertises custom wheel spacers. They look to be about $130-150 pair for thin ones. You can certainly specify thickness since you could run up to a 15mm with no issue. You would have to run extended studs.
http://www.serpentautosport.com/HTML/Hub Adapters and Spacers.html
Michael Hurd may have some input on what to look for in terms of a good machine shop or recommendations.
Good luck man, the wheels look real nice. Can't wait to see pics when you finally get them mounted.