As a builder of more than one John Smith type organ, my suggestion
is to voice the pipes using the wind supply they will be playing on,
i.e., the organ itself.  The late Brian Flora and I had many
discussions about this.

Organ pipes are most stable when voiced on a wind supply approximately
that which they will eventually play on.  Pipe builders use a voicing
machine in which the wind is variable in pressure.  Mechanical blowers
are usually pretty reliable from organ to organ or from pipe voicer to
organ.  The pumps in a John Smith organ do not in any way resemble a
mechanical [turbine] blower.

If you use such a machine for the John Smith pipes, I can almost
guarantee you that when placed in the organ you will have problems
with their proper speech.

My dime worth.

Ed Gaida
San Antonio, TX