How big is your fermenter?
With a lot of IBU's you'll need some extra gravity to help balance it out. I know the expense is high, but you'll get a lot more mileage out of a bigger beer like this.
I am going to assume 5.5 gallons into the fermenter.
If you add 2# DME your gravity should be around 1.039
If you add 3# DME your gravity should be around 1.047
If you add 4# DME your gravity should be around 1.055
I know it's an extra $10, but it'll be worth it.
As far as color I'd go with pretty much the lightest color they have. All my extract beers are always too dark either way.
What kind of yeast are you using?
BTW: To cut down on cost a little I snuck pilsen light DME in my English Bitter and saved a couple bucks. The 3# at LHBS was $11.79.