Hi Ed,
I don't know whether you found a solution to this post and whether it's still relevant. I went through the same process many years ago as part of our organisation's migration from Workstation Arc/Info to ArcGIS. To migrate our customised IGL fonts to TTF, I wrote an AML that converted each IGL font character into a coverage, then displayed the coverage in ArcPlot to create a graphics file which was then converted to Postscript format. The Postscript files were read into Corel Draw and saved out to TTF. Some symbol characters were saved out to EMF for creating ArcMap style symbols.