Putting 18"s on my 1990 GT, need fitment advice.....

I have a 5 lug 4 wheel disc brake conversion on my 1990 GT. Installed using SN95 spindles in the front, and NRC rear caliper brackets supporting 95 calipers. I know the 87-95 wheel offset stock is 24 mm, how far can these go in without having spacers? I am thinking about the 2003 SVT Cobra wheels in a 18x9 front and 18x10 or 10.5 rear, front tires are going to be 245/40/18 and rears will be 275/35/18. What do you guys think? Any suggustions or advice is welcome, also anyone know if there is a website that has a great selection of Fox's with 5 lug wheels?