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.