As a licensed Master Electrician, I would refer to the National Electric Code, table 310.4(1), conductors rated for under 600 volts. I would be looking for a conductor that has a maximum temperature rating GREATER than the highest setting of the thermostat. Maximum conductor operating temperatures in this table range from 140f to as high as 392f. Specialty wires go even higher. Looking for replacement conductors, I would go an appliance repair shop and purchase conductors for use in a range or oven. Ranges and ovens use conductors that are suitable for 500+ degrees farenheit. Size the conductor for the load applied. If the press is rated at 15 amps, use #14 wire, 10 amps would require a minimum of #16. In addition to the temperature you need to be aware of the flexibility of the conductor for when the press is opened and closed. Do not use a single strand conductor. The more strands the better.