Since you're wanting to port it...
2.0 gross is going to be on the small side for most 12's but should be adequate. If that is your volume based on external dimensions then you probably only have 1.8 or so internally, after sub/port displacement you'd be in the 1.5 cf area.
For a 10 you'd probably be ok. Somewhere in the 1.5-2.0 range (gross) should be good.