Have you thought to have the originals rewound; Peter Dahl can do it for
you. He does stock your main power transformer, at least the one for the
HT-37 but is not cheap $235 (!)
http://www.pwdahl.com/dahlcatalog/hamtrans011404.html#H
Here is another outfit that rewinds transformers.
http://www.jenkins.com/jenkins/transformers/rewind.htm
Ken