There is NO AI Classic to AI2 conversion tool except for your imagination and re-coding the AI Classic app into AI2 manually.
At one time there was discussion that a tool to the conversion might be available sometime. It now appears there either will be NO tool ever or the tool, if anyone makes it will not do a complete conversion.
If you have AI Classic projects that you want to run, either re-code the projects now or search for an AI2 equivalent project in the MIT AI2 tutorial section or find a similar AI2 projct on the Internet. Many AI Classic coders have posted AI2 versions of their tutorials (but not all).
Consider, support for AI Classic is supposed to disappear sometime this Fall.
Regards,
Steve