bigger rear disc in rear than front a problem I assume?

One kit I'm considering is 140-14271, that hub is listed as 2.76" and I could not get a caliper inside the cop wheel to measure, but measured the hubs on my 74 disc brakes and that measurez 2.8", so it will fit BUT it states it increases the track width .26", so I'll need to mount the wheels again and see if I have that much room to clear inside the fender