Dear Matt, Greetings from The Bronx.  While your desire to resurrect
the former reproducing grand is to be lauded, the likelihood of finding
the exact player stack for it is going to be your biggest dilemma.  All
other components of the reproducing system are mostly identical to all
other piano installations, be it Steinway, Weber, Steck, Stroud, and
Aeolian, etc.

The problem arises from the scaling of the piano action, with it's
several sections or breaks (usually 3 or 4).  Another possible problem
would be if the control linkages are also missing (levers to engage the
player system, from the front fold down keyslip).

The size of the Steinway XR's piano harp is the same as the non-player
Model A.  The difference in sizes, XR = 6'1" and the Model A = 5', is
attributed to the fact that the keys and front of the XR is extended
approximately 11" to accommodate the upper portion of the player action
(spoolframe, roll motor, etc.).  Another thing to be considered is if
and when you find all the necessary Duo-Art components, they will
inevitably be in need of a total restoration before being installed.

An alternative to this Herculean feat is to consider the installation
of a digital player system such as PianoDisc, Pianomation, Disklavier,
Chase E-roll Player, or Wayne Stahnke's LX system.  As the XR had
already been a player in the past, very little preparation would be
needed for a quicker-than-usual installation.

A plus for these systems is that the availability of digital music
files is practically endless.  Some systems will play files designated
for one or more of the others, and most will play general MIDI files
which are available for download on the Internet.  There are also files
of scanned 88-note and reproducing piano rolls available on the
internet from

  http://www.trachtman.org/rollscans/ 
  http://www.spencerserolls.com/ 
  http://www.petersmidi.com/ 
  http://members.shaw.ca/smythe/archive.htm 

Some of the aforementioned web sites have piano MIDI files free to
download and distribute, whilst other are strictly for sale only.
The last site listed is totally free to download and distribute; this
site also offers information regarding the various types of rolls.

Hope this is of some help,
Sincerely,
Dale F. Rowe
Bronx, New York