Arc welders need to handle very high currents. This requires very heavy, thick cores. Out of the options you pictured your best bet would be to rewind the secondary of the one in the center (the one you're holding in the second image). However, there may still be other issues that would prevent any of them from working. You'd really need to go into the theory of transformer design and come up with actual specifications for your welder, and size your core and windings accordingly.
If by Arc Welder you mean SMAW then the typical SMAW transformer has a magnetic shunt, the open circuit voltage is in the region of 70v to 100v, this voltage is necessary to strike the arc, once struck the normally high current causes the voltage to drop to just a few volts due to the effect of the shunt.
A spot welder is very low voltage, high current, it does not posses the very high open circuit voltage of the SMAW.
Max.