To change to a capacitance type fuel senders would be a huge undertaking, including removing the tank, drilling out the rear baffle, etc.
A faster fix would be to just fix the sender units, which is exactly what I would do. Or, I would get some better fuel gauges, such as electronics international, etc which can be calibrated to virtually any ohm range. Be aware that the float type senders will only show a change over the last 15 gallons in the tanks since any larger quantity of fuel will have the float at the top of the tank due to the dihedral of the wing.