The only Weld's that fit are the discontinued XP's. They're 15x8. I'm not 100% on the backspacing, but I believe it's 5.5". He'll need to relocate the rear sway bar (BMR sells a kit). I think he'll need 3" lugs and may need a spacer.
Right now the only ones being made to fit our cars are by Bogart. They're about $800 for a rear set and custom made. Greg Weld is working on some right now, but the first ones they came out with didn't fit right. They probably won't be out this season.