Northern Brewer Extra Special Bitter--Additions?

I'm planning on brewing the Northern Brewer Extra Special Bitter. I would like to bump up the ABV a little bit in this beer, and thought about adding an additional pound of light DME. Of course, I know this will throw off the bitterness and I would need to add more hops. I have the two ounces of Williamette and UK Kent Goldings that the kit calls for which will be used, obviously. Would any of these hops I currently have work as an addition for this ESB?

I have:

2 oz Centennial
2 oz UK First Gold
2 oz Millennium
2 oz Falconer's 7C's Blend

If any of those hops would mesh with this ESB, I think I'll bump up the extract, if not I'll leave the recipe as is.

FYI, here's the recipe/kit:


SPECIALTY GRAIN
- 1 lbs English Medium Crystal
FERMENTABLES
- 3.15 lbs Gold malt syrup (60 min)
- 3.15 lbs Gold malt syrup late addition (15 min)
- 1 lbs Briess Golden Light dry malt extract late addition (15 min)
HOPS & FLAVORINGS
- 2 oz Willamette (60 min)
- 1 oz UK Kent Goldings (15 min)
- 1 oz UK Kent Goldings (1 min)
YEAST
- WYEAST 1968 LONDON ESB YEAST

Any help would be appreciated!

I'd use the UK first gold.

Thanks for the reply. Should I add just one ounce, and where in the boil should I add it?