I'd prefer to get some hub centering rings personally. The Mustang wheels with that offset should work fine. I would mount one on the car without a tire to see how much clearance you have to the inside, you *might* need a small spacer, but I don't think so.
WOWZA, thats a lil more work then im willing to do. that thing must turn in mad. thanks for the pic.
i ended up ordering 235 50 18 kuhma ecsta asx. a little taller then stock. i figured it give a smoother ride, fill in the wheel gap, possibly better mpg due to less rolling resistance and higher gear ratio and have better clearance then the 245 45 i was looking at the price of performance/handling.
hopefully i didnt make a big mistake with the 235/50/18, i could only find one person with them on a 2gen. however they did love them. they are ,gasp, 3.4% difference then stock 18" tires(2.9% compared to stock steelies). almost 1" in height. so ill be going 65 when it says 62.79mph. i like the idea of more cushion and less wheel gap. i just hope they dont look out of place and dont rub.