To add my $.02 worth: The early 80's recordings of Waller piano rolls
played on Compton Pipe organ are still widely available on CD and are
fun to listen to.  Julian Dyer correctly notes that using only the
Great manual creates some problems.  It is probably a result of
technician thinking rather than musician thinking.

Inspired by the CD,  I came up with a transposing board with cables
to use my 9-per-inch Wurlitzer Style RJ player to play piano rolls as
well.  I watched some Waller and other stride piano rolls as to where
the bass notes and left hand chords fell, as compared to the right hand
melody.  I decided to wire the player as follows:

  Pedal: Low C to second F
  Acc:   Second F# up past middle C to F# above middle C
  Solo:  G above middle C to the top C of the organ.

The last 12 of the piano remain unconnected as do B, B-flat and low A
of the bottom of the piano.

This keeps the bass notes and accompaniment (acc) chords on the pedal
and acc manual most of the time, although there are sometimes some
obvious crossovers as a line ascends or descends the keyboard.  And
it enables use of the 16-foot stops on the Solo manual so the sound
is not so high and squeaky when the high notes are played.  This also
prevents the odd effect that bringing in the 2-2/3 or 1-3/5 has on the
CD where they can be heard in the left hand as well.

Incidentally, the player on the Compton was wired one whole step (two
notes) flat, so that anything Fats played in C comes out B-flat, F
comes out E-flat, etc.  Perhaps this was a way to deal with the bass
notes often sounding too high for organ pedals.

Incidentally, when I decided where to divide the manuals, I did not
know that Wurlitzer Concert Organ Rolls divided the manuals between
F and F#, only one note different from my guestimate.

Right now, my player is inoperative, having never been rebuilt and
in need of some tender loving care -- all I need is the time (HAH!).

Love reading all the items in the MMD.

Oh, and by the way, I am studying launching a 24/7 all-instrumental
music web site: $4.95 month for all the instrumental streamed music you
can stand, including a theatre organ, an automatic instrument and ? or
live ragtime, a 1920's and/or 30's dance orchestra piece every hour,
with the rest being movie music, jazz, big band, instrumental rock
novelties, harpsichord, bluegrass, new acoustic, etc, etc, etc.  I'll
keep you apprised.

Thanks
Ken Rosen