Adding AC to Duster

The firewall may be slightly different but it might still be doable. What you would need is another similar car with factory AC to do a careful side by side comparison. Find some common reference points and then take careful measurements to find out where the openings need to be. At the same time measure and check the position of other heater/AC components that protrude through the firewall such as the heater lines and blower motor to make sure that they are in the same position. You have the parts you might as well make the comparison, note the differences, and determine if it can be done and still look good - or not, if staying cool is of a higher priority. Make the comparison and tell us what you find out.