I am somewhat suspicious of this combination.  There are two logical
explanations, however.

The piano might be a _"Chickering Brothers"_, which is not a product
of the American Piano Company.  Another clue that something is wrong
is the reference to "Style A" piano.  The Chickering piano produced by
American Piano Co., that is 5' 4", is known as style "52" with a 135
string scale.  The number 135 is usually cast into the plate at the
rear.

It might be a custom installation.  I have no knowledge that
Welte-Licensee mechanisms were installed in that manner, but Ampico
did a brisk business installing their units in any piano.  The shop
was in New York and Alf Werolin worked there as a young college student.
Alf has told me of his experience in this regard.  Alf's father was head
of the Ampico Service department, and  references can be found on that
subject.

It should be noted that after about 1925, American Piano Co. built
straight pianos that were prepared for installation of the Ampico,
(or any other player).  The main beams were parallel and pre-drilled
with large holes for the main hoses leading from the pump.

Bob Taylor