As the recipe stands, for a 5 gallon batch I figure you're looking at a 1.059 starting gravity and would plan on finishing around 1.020. That's a 5.1-5.2% ABV.
Sub in light extract for the dark and would think you should be able to finish around 1.015. That's about 5.8% ABV.
Your yeast is going to be a factor. I would certainly use something like Nottingham or US-05.
I haven't used dark extract in many years but have noticed that people will post higher finishing gravities when brewing with it. Like I said, it's just a suggestion. What ever you use, keep notes. With a little experience you can make almost anything work.