Is your original speaker reparable? Torn cones can be patched. Really destroyed cones can be replaced if the field coil and voice coil are still working. You'd get the best results by fixing the original speaker if possible. A picture of your speaker cone would be helpful. Here is a thread showing how to recone:
http://www.antiqueradios.com/forums/...3e19facc1743b6
Another thing you can do if the field coil is still good but the cone is bad and you don't want to have it fixed, is to install the old speaker in the bottom of the cabinet or under the chassis shelf to keep the field coil connected, but disconnect the voice coil connections to its cone, and extend them to a new permanent magnet (PM) speaker that you install in the normal location. The PM speaker should be 4 ohm but 8 ohm will work.
If the field coil in the old speaker is bad, take the output transformer off of it and install on the new PM speaker or somewhere close by in the cabinet. Connect the voice coil wires. The field coil of the old speaker was necessary to provide magnetism for speaker operation, and also to provide filtering for the radio power supply. You can substitute a power resistor of about the same resistance of the field coil. The schematic says your field coil has 2100 ohms resistance; you can use a 2500 ohm power resistor rated at 10 watts. One source for these is JustRadios; they show them for 79 cents each. Install it under the chassis somewhere where it will have air circulation and not be too close to any other part; it will get hot. You can use a higher wattage rating, too, for the resistor to operate cooler. The resistor will not do as good a job of filtering as the field coil did, so replace the filter cap marked as 20 mfd. 400 volts with a new one 47 mfd. at 450 volts. The other filter caps should be replaced, of course. You can do this under the chassis as new caps are much smaller than the old ones. The old caps should be disconnected.
Edit: I thought this was an entirely new thread; now I see you were discussing this radio already farther down on another thread. The radio is working now but you say you hear distortion. Before considering replacing the speaker, connect any PM speaker you have via test leads to the voice coil terminals of the old speaker. Listen to the new speaker. If you still hear distortion, the speaker isn't the problem.