As I remember the 'curve' is most non linear and difficult to achieve any accuracy... traditional 3 point methods don't work, probably why they see limited usage (at least the old ones) as a matter of fact a common silicon diode is easier to calibrate to 2 - 3%. It would seem to me to be much easier to use a thermocouple. There are several companies that provide the necessary cold point compensation as well as provisions for the different types of junctions (Gain Adjust) thus making an interface that is Much easier to use.
Just a stray thought as everyone has a different method of solving a problem and sometimes it is good to make a list of the options and carefully consider all sides first.
Doc