Yeah, that is the plan. I'm just curious if there's any way to have the street-facing windows restored to their original functionality before we replace them all, which will significantly change the look of the house.

Can you post up some pictures? As a general observation, we don't consider stuff from the 50's as antique and usually restoration quality. That said, some pictures will help.

Most of your restoration candidates are going to be weight rope type windows with good, old wood frames and some historic charm.

you could cut them down and modify them to run on a vinyl track/ jambliner. There are people who specialize in this but they are becoming harder to find.

You could also do new sash kits which would preserve the look much better than an insert type window.

We did wood sash kits in our old wood windows. Those on the weather side are clad Kolbes. On the lee side, where the windows are under a large two story porch, we opted for primed sash and painted them ourselves.

Advantage of sash kits is that you don't need to remove any trim and replacement is fast and relatively easy. Other advantage is that you don't lose any glazing surface (unlike the 'pocket windows'). Might not be the very best but a huge improvement over the old single pane windows that the kits replaced.

You need for the jambs and sills of your current windows to be in good shape to use the sash kits.