Hi Anand,
thank you very much for your question, however I believe you are trying to achieve something impossible.
You are asking for 24-bit resolution which usually requires a Delta-Sigma converter. We only have one Delta-Sigma ADC in our portfolio that can run at this high data rates, ADS1610. However this is a 16bit device and the SNR that you can achieve at this high data rates is in the 80dB range. So far from a 24bit resolution.
ADS1675 would probably be one device that would come the closest to your requirements. But you will have to use two of them in parallel and synchronize them in order to simultaneously sample two signals.
Regards,