Duane,  I would say that converting a regular reed organ to being
a player would be a task that boggles the mind, but there are things
that you could do to start from scratch -- or take the simpler route
and buy an unrestored Orchestrelle and restore it.

Starting with the basics: would you want it to be suction or
pressure?  Assuming a suction model (as most American reed organs
were suction) you could start with a reed chest from a reed organ and
build a pneumatic deck that simply pulls the pallets open when the
note is played.  Your keyboard could be in-line with the tracker bar
and simply open the same holes when you play a note; alternatively,
you can simply have the direct pushing action that is common among
reed organs.

The roll mechanism would be the same as for a regular player piano.
(How many notes do you want it to play: 58, 65 or 88)?  Most organ
rolls are 58-note and typically a lot of piano rolls do not sound
good on the organ without major editing.

Still, why not take the easier and perhaps better route and buy an
Orchestrelle in need of restoration?  There are many of these fine
instruments that need some TLC (they are relatively inexpensive),
and when restored they sound fabulous...

Eli Shahar