The 17" Focus rims will fit the SVT. Both are 4x108. The lower the nuber on offset, the more the will will stick out toward the fenders.
Stock SVT offset is 49.5 on a 6.5 inch rim. The wider the rim, the lower offset number you will need. Most 17x7 rims run an offset of 40-45mm.
I think the Focus SVT rims are 17x17 with a 42mm offset. They fit nicely.