Measure the saddle-to-bar distance on the ol' Antelope, and then do the same on the Surly, making sure to measure to a line even with the base of the brake hoods. All of my bikes, as it turns out, measure within an inch or so of each other. If yours are radically different, you may need some help to figure out what to do, even if it's just swapping to a shorter stem (some shops will simply give you a stem, so yours might be similarly helpful).
Still, you've put a year's riding on one bike. Changing to another one with a different riding position will take some adjustment. Your shop will likely help more with adjustment, including maybe changing the saddle position again or whatever else you need. I'd think that a 62 cm is a good size for you at your height (maybe a 60, or a 61), but, as always, we're all proportioned a little differently and what works for one 6'5"-er might not work for another.