Kawahara tires have no offset in the front and +1 mm offset for the rears.
If your car is oversteering when you are getting on the throttle, the easiest fix would be to go with a thinner rear diff oil.
A solid front axle will scrub a lot more speed when you are coasting into corners, and will also tend to lose some initial turn-in for obvious reasons. But for the FW, less off-throttle corner speed could be a good thing, because it coasts so much.