ok heres some info
1. All IS350's have big brakes they are not only limited to F sport and X models
2. if you want wheels to clear you need the right disc type on the wheels itself for work wheels
3. a good fitmemt size on a is350 with minmal lowering is 9 width front and 10 width back with mid to high 30's offset ie 35 onwards to 40
if you want to lower your car and not have any fitment issues with the guards i suggest 8.5 and 9,5 rears with around mid 30's offset
any lower offset you will have to roll the guards and run camber
if damaged wheels are the only reason why you want to change the wheels
i suggest getting another set of wheels in better condition as they are around and expect to pay around 1K more or less depending on the tyres it has