Ran finding aids through "EAD version 1.0 (XML) to EAD 2002 Conversion Package."[1] This tool works well, but there are several things to note.
The XSLT assumes ISO-8859-1 encoding; this can be modified for
UTF-8 if necessary.
Inspect and edit user-defined variables in v1to02.xsl as necessary.
Inspect the output to make sure there are no surprises, such as
<language>[code "en" not found in ISO 639-2 list].</language>
Ran the resulting EAD 2002 finding aids through an XML validator.
[1] EAD Help Pages - EAD v1 to EAD v2002 Conversion http://jefferson.village.virginia.edu/ead/resources/ead2002conv/