Dear Steve,  Greetings from upstate New York.  There is probably no
need to build other types of pipes for your project.  What I would
recommend is finding an organ builder or service that could take the
present replacements and having them re-voiced.

What they would probably want you to do is bring them maybe two or
three pipes of the other ranks, so they could establish at what
pressure they are tuned at.  And after they've established the pressure,
they will re-voice the pipes by re-positioning the cap to redirect the
airflow across the upper lip of the pipe.  They may even reduce or
increase the airflow through the pipe toe.  Hope this helps.

Sincerely,
D.F. Rowe
Newark Valley (Bronx), New York