Hi MMD and John,  In my limited experience, the doorways are more
expendable than the piano.  I have an Ampico upright that I have had
in and out of six houses in the last 40+ years, including the basement
in two of those houses.

The first time, I hired professional movers and they had to stand the
piano on end to get it around a corner.  A year later when it came back
out, by pure chance, I was lucky enough to have the same moving crew.
So they knew just what to do.

In several cases, I had to dismantle the doorways, and in one case
I even had to take out some of the dry-wall and a stud.  I put the stud
back in place with lag screws because I knew I would have to repeat the
process when the piano came back out.

A doorway comes apart very easily when attacked with a measure of care,
a thin, wide, putty knife and a small hammer.  Start with the molding,
and when that is off, the door frame can come out.  Be careful and you
won't damage or split any of the boards.

Have fun,
Pat DeWitt