About model and data exchange with 3rd party solutions: Revit, Solibri, dRofus, Bluebeam, structural analysis solutions, and IFC, BCF and DXF/DWG-based exchange, etc.
Due to the infancy of IFC back in 1997-98 (AC 6.5) there wasn't much IFC support. Even if there was an IFC translation add-on in that old of a version, the IFC version format would pretty much be useless by today's standards.
I can't locate 6.5 IFC right now, but I don't know which OS you are on. It should be available though Graphisoft's website as a download. If not, email your reseller.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"
Graphisoft's IFC Support download page only lists back to AC7.0. I don't know if it is because the older versions can't support IFC or if it is just Graphisoft's decision to not support versions older than 7.0.