You'll need more inductance than just putting ferrite cores on the wires. Some old PC power supplies might have the right kind (they'll feel heavy and the inductor you want would be screwed to the case), but an easier source is to find some old microwave oven transformers and cut the welds so that the part of the core that looks like an "I" can be removed. Then remove the secondary winding and put a 0.5mm or so non metallic spacer and put that piece of the core back. (If you have an inductance meter, use it to get the spacing just right.) The inductance is not going to cause any problems for the inverter since the H bridge will have catch diodes. They don't like capacitance and standing waves, which is what the series inductors prevent.