[morzh]

What you will have to do (and I would advise against it unless it becomes a necessity - try to align the speaker first) is:

1. Get the speaker with the proper voice coil impedance. If not possible and the impedance difference is too great (like 8 Ohm vs 0.67 Ohm) you will have to change the output transformer or the speaker will not work very well.
2. In case the radio is small and the coil was not used as the filter this would be it. But it is rare.
3. If it is used as the filter: Replace the field coil with equal or close value inductance choke. This will have to be mounted on the chassis or special precautions used not to propagate interference using long wires (twisting etc).
4. The choke has to be current rated at least the same or better as the field coil.
5. The DC resistance of the choke has to be very close to what it was in the field coil. If it is lower a series resistor of the appropriate wattage has to be added.
6. Last. In some Philcos a capacitor across the choke is used to minimize ripple (works on phase differences). If the choke is different it might not be effective. So the value may have to change, or the cap might not even be needed. In any case, the second cap after the choke can be increased without much ill effects and this will attenuate the ripple more.