I think I might slide on the flange then put the hub and rotor on, bolt the rotor down. You could then make two rectangular bars that have the correct brake gap measurement and then clamp the rotor, bar and flange all together top and bottom, This way you know its true to the rotor. That sort of what I did on my kit but I leave the old flange in place and weld the new flange on to it. I use the caliper bracket to position it true to the rotor
