It is my opinion that the most important consideration with rare
instruments is to keep them original.  What is done is done to the
pianos.

The parts from the Vorsetzer might work, but I can't imagine that they
would in any way resemble an original installation, at least without
extensive modification.  Keep the Vorsetzer intact.  Most of them have
been destroyed by now.  Maybe the right guts will appear for the pianos
some day and wouldn't the roll cabinet that used to be a Vorsetzer feel
left out?

I know that there are [Welte] T100 Steinway guts in at least one
unlikely place in the US.  I have a friend who has been hoping to
acquire such a set unsuccessfully.  There must be others.

Spencer Chase