I'd follow my heart and find a good salavage shop and get the single-glazed windows. You could always fudge it down the line if they aren't doing the job keeping the chill out by adding insulated doors to either the inside or out....kind of like a over size shutter which would also be staying within the period. Just have them frame the doors on the jam so you can add another set of doors to either the inside or out when you put them up.
I've a 1830's house with French doors on what was once a open back porch..when I went to paint them I noticed there were hinge marks where another set of doors were on the outside of the French doors.

Check out your local or regional Habitat For Humanity ReStore. They sometimes have them. We bought a pair of vintage French doors salvaged from a historic Santa Fe house for $250., much less than anything we saw that was new. They're beautiful and have art deco brass hardware.

Salvage shops are great places to shop if you are looking for achetecturally correct itmes for an era. If they don't have anythng at the time you are there they keep their eyes open for you. Besides poking around them you can find a lot of other treasures that would look great in your home

some practical issues:
Old wood doors will expand and contract with the weather. So they will need weather stripping or be drafty periodically.
Out swinging doors if left open in bad weather will get wet - not so good. Consider having them swing in. At least be sure your doors are ext. grade doors (different glues used) and are finished for outside conditions. Outside doors are usually thicker (min.1 3/4") than inside doors (1 3/8").