The good news is that you have a really good shooting gun, the bad news in your case is that the current set up is a bit too tight for mostly 25 yard shots. Under duress with a Tom in your face and you will miss some birds at some point with your current pattern.
I bet the .600 factory choke will come real close to that 250/250 you are desiring, and I agree that would be a real good hunting pattern for anyone inside of 40 yards. But I only chime in to say this, if the other factory you have ordered does not work, you might could try the anaconda striker in .570 from Patternmaster, which has gas over constriction. In three guns we have shot it in, that set up runs between 245-285 in the ten, and then usually around 230 or there about in the twenty. I think that the choke you just ordered is going to do the trick, but if not, That choke I refer to is only $59.00 from Patternmaster.