Temperature conversion ADC0804 and LM35
My first response is that you should probably move up to a more modern approach to this project. Using LM35's and LM741's is technology that is about 35 years old. You can do a lot better and much more simply that messing around with the likes if these ancient analogue parts. 

Research digital temperature sensors that have an I2C interface using just two digital signals. There are a plethora of candidate chips to use for this and they will provide you a wide range measurement capability often with resolution down to 0.125 degrees.

The temperature sensor with the I2C interface is then connected to an MCU of your choice. The display is in turn connected to the MCU and software takes care of reading temp values from the sensor and sending the values formatted to the display. Again there are scads of MCU choices and display choices can range from LED segment, LCD character or OLED graphic.