It looks like Undallas gave you a ton of good answers.
It might be best to save the extra ounce of simcoe for a bittering addition in another recipe and use something else for your dry hop (cascade maybe?), but that sounds like it might be more complicated than you want.
The only other thing I think I can add is that you might want to try Beersmith (google it). I haven't tried the program that Undallas linked since it didn't want to work for me under Vista, but I've been very happy with Beersmith. They have a full featured three week trial. After I used up the trial time, I was more than happy to pay the $22 for the registered version. It's a great way to tweak ingredients to see what effect they have on late additions, IBUs, etc.
Now go make some beer and let us know how it turns out!