Always oversize inductors at least one size where possible. 20 gauge inductors cannot handle more than around 180 watts. 18 gauge inductors are usually good up to 250 watts. 16 gauge inductors are usually good up to 500 watts. 14 gauge inductors are usually good up to 800 watts.
Inductors have resistance, and can be checked with an ohm-meter.
Keep in mind that these power ratings relate the load an individual speaker will carry, not an entire system. If you have 4 speaker cabinets per side and 400 watts driving them, its likely that each cabinet will see 100 watts of power on average. This is what you need to scale for. Never drive your speakers harder than they are rated for - you will destroy them long before a properly sized crossover component. The information given here implies that you can only use a low frequency speaker and a high frequency speaker.