The short answer is yes...
The speaker itself WILL fit all the way down in the pommel (any pommel that can fit the standard disks, that is) but you'll need something to hold it in place. That's where you're gonna have to get crafty, because none of the speaker mounts that I know of will really fit perfectly for this situation. You might try making a fixture that can fit snugly in the female part of the choke and attach that to the speaker to hold it down there (you can stick the back of the speaker to it with some kind of adhesive pad, or even glue, just be careful not to get any inside the speaker).
Let us see it if/when you get it done!