Globally change fonts used in a graphic

Running IsoDraw 7.3 on Win7 pc.

Using Batch to convert CGM files to SVG.

Would like to remap all Fonts (most are Arial), changing them to Helvetica.

How to batch change the Fonts, whether in the file while it's open, or during the batch export process?

We certainly could write code and run it against the SVG files afterward, but will IsoDraw do it?

Thanks,

Dave