Hi, John -- Terry Smythe, who is responsible for a lot of startling and
exemplary initiatives in the field of mechanical music, has collected
the information you are looking for.

On his page, "Player Piano Rebirth," Terry is running a section about
e-Valve equipped pneumatic instruments.  There you can learn a lot
about past and present solutions, including commercially available
items and ideas for the hobbyist.  Also one of Terry's offsprings is
the Yahoo e-group about e-valves.

When you have added MIDI control to your Ampico grand, you will be
in need of special MIDI files.  There is another Yahoo group which
is dedicated to E-Roll Collectors.  If you want to know, where and
how these files originate, have a look at the group for Rollscanners
or Mechanical Music Preservationists.

A lot has been done and a lot of people are waiting for you to share
their information with you and to get another fellow combatant.
Go ahead!

Walter Tenten