It's 53 x what that's the question.
Your tallest gear will be taller. But gear by gear, they'll just be different. First thing I'd do if I were you is look at a gearing chart, figure out which gears give you the most trouble (e.g., when you're in your 50, do you wish you had a 16-1/2 in back), then find a gear combination that will give you a happy cadence at a happy speed.
I think if I were you, I'd put a 39 in front in place of the 34, and go back to the 12-27 (or 11-27 if you want a taller high gear). But before doing that I'd figure out how many of the low gears, that you do use, you'll be losing.
Speed comes from what you put behind you. - Judi Ketteler