This magnetic core is very bad, it saturates with an induction of about 0.6T (6.000 Gauss), it can not serve anything except to be sent to recycling. With crap core, you will only make a crap inductor...
As for the inductances for crossover, it must be linear to avoid distorting the sound.
It is therefore necessary to use either inductances without core, or with a good quality core with a large air gap to linearize its inductance curve.
It is not possible to use this magnetic core because:
1) the steel used has very poor ferro-magnetic properties. Even working with a low induction, hysteresis losses and Eddy current will be far too high at higher frequencies....
2) It is very difficult to create an air gap, it will be necessary to saw the core. Even so, the gap will be probably too little.
Inductance of crossover must be of very high quality, no way to use a crap core who does not even serve to make a 50Hz transformer.....