It's possible but mind the following:
1. The 670 software version must not be lower than that of the 100.
2. Place the cards in the same slot numbers. But, if you have a T1 card with more than 16 channels in slot 103 on the 100, then slot 104 on the 670 should be empty.
3. Make sure you have enough licenses and the right kinds on the 670.