Personally I would go with a wider rear wheel, like a 10. But the 8.5 in the rear won't need a spacer because of how small it is, it shouldn't interfere with anything unless it has break clearance issues, and the front should be fine as well, but likewise I would go with a wider wheel, say 8 or 8.5, you could try putting that rear on the front but I think it would stick out about a .25 too far. I work for a wheel company and we've put 18x8.5 with a 44 offset on the front and a 19x10 with a 50 on the rear. These offsets on these sizes line the outside of the wheel very nicely with the fender. Going with smaller wheels you would want to decrease the offset an amount equal to half the change in width as to not stick the wheel too far under the car. So IMO ideal offset on a 7" front wouth be 25 and for a 8.5" rear 31. So I'm guessing .5" or 13mm spacer on the front and a .25 or 7mm spacer on the rear for looks only, not funcionality. If you are buying these wheels, I could make the spacers for you, in whatever sizes you want. Let me know.