Well the port should always be there, it was there on the Mk1 as well:
The little resin piece to the left plugs the port. On the SR-007A's I've owned there was this black cover of the cable entry but it creates an airway to the outside instead of sealing it completely. Here is the first set I got:
This appears to be sealed on the new Mk2's as both sets I heard were 100% stock. Clark had one and the other was in the Woo room.
If somebody wants to try the port mod, then it looks like this: