There's literally a TON of threads on here about back spacing (BS) and Offset etc.....
I have the Level 8 MK-6 wheels also in 17". If you plan on clearing the bigger calipers for the TBU then you need the -10 offset or a wheel spacer. I didn't want to run with wheel spacers. If you're worried about clearing your UCA's the level 8's have plenty of BS with 5.5". Without going into too much detail, I hope this helps.
EDIT: I also have the SPC UCA's and no problem. Also, with the sport edition I didn't want my tires to extend much past my flares. Check out my build and you'll see the wheels in there somewhere. If you want a side photo to see how far they protrude, let me know I have one.