How ACCURATE is the final system to be, given the uncertainty of each type of thermocouple. And I have yet to see a 24 bit converter that is 24 bit accurate, when you look closely, you'll be very lucky to get 16 bits.

CCJ can be done by measurement of the "Cold junction", and calculating the required offset to your current reading.

An 8052 can do it very easily - I used 8052 Basic for mine.

Steve