Sounds good to me, the brown sugar should add some delicious.
However I wouldn't add it just for an ABV% boost. I would fear it throwing off the GU:IBU ratio and ending up with something unbalanced. Personally I'd just wait to brew the recipe again and make it stronger, also adding the additional hops to make it balanced.
Just for s**ts and giggles, if your OG was 1.060 then adding 1.0lb of brown sugar will get you roughly to 1.069.