The original Concert Bass (black and silver face) was rated at 150W@4ohms. Running one 4 ohm and one 16 ohm cabinet might work, with its total load of 3.2 ohms, but I wouldn't count on it. Besides, the 16ohm cabinet would be getting only 37 watts. Not worth risking your amp over.
The second generation Concert series (black face with red knobs) was supposedly rated at 200W@2ohms. Joe Arthur says he wouldn't trust them at a real 2ohm load, and I trust his judgment on this. However, they'd probably be okay at 3.2 ohms.
If you wire both cabinets for 16ohms and run them both, you'll get 80 watts out, IIRC. The difference between 80W and 150W is only 2.7dB, which will probably be more than made up for by the second cabinet. That's the way I'd go. You could also add another 8 ohm or two more 16ohm cabinets later, if you feel the need.