Why are you adding a motor?  If you are unwell or unfit so need help
that is okay, but if the organ is leaking it would be kinder to get
the bellows re-covered by a player piano technician or local firm of
pipe organ builders.

I would recommend British Organ Blowers in Derby, England, or Watkins
in Hampshire, England, but don't know who to suggest in USA.  You need
to tell them that the instrument uses about 2-1/2 inches pressure and
also the fact that is has seven rows of reeds (yes, one rank has twin
reeds) plus a sub bass.

Also mention that the roll motor uses a huge amount of air, say 35%
of total requirement, and then get them to add on 25% to capacity of
blower.  You need high volume, low pressure.

There is sometimes an inlet flap waiting to be used on these instruments
at the bottom of the bass end stop tower round the back; this is the
best place to feed in the air supply.

I hope this helps,

Kevin McElhone,  Archivist M.B.S.G.B.