Brewers Best Imperial Pale Ale ...adding more hops?

I have the Brewers Best Imperial Pale Ale ingredient kit http://www.brewersbestkits.com/pdf/New BB Recipes/1045 Imperial Pale Ale Recipe.pdf that I will be brewing this weekend, my first brew. I've been helping out a hobby hop farmer this summer and have about 4oz of his Chinook (vacuum packed & in freezer) and am thinking of using those instead of, or in addition to, the 4oz of Columbus included with the kit. Any suggestions? I do like hoppy ales but don't want to go overkill with this brew. Initially I was thinking of using the Chinook as the bittering and using the Columbus for Flavoring and Aroma. Your thoughts?

Thanks,
Jay