Mike,  you might try some organ builders and organ repair persons who
have been in business a long time.  Somewhere in their warehouses they
might have some lead tubing that was used in tubular pneumatic pipe
organs.  I suggest Richard Schneider of Schneider Pipe Organs, email
rich@schneiderpipeorgans.com.geentroep [delete ".geentroep" to reply].

With the predecessor firm (Gratian Organs), the firm has been around
a very long time, and he has a huge old warehouse full of who knows
what.

You might also check with Brian O'Bannon on Facebook.  His father had
a large piano shop and retired fifteen years ago leaving everything in
place.

Dennis Steckley