IIS 8.5 is supported by for hosting PIABWS web applcation. However, you will need to refer to KB article kb0009024 to allow clients access if you experience IIS error 500.19 http://www.projectinabox.org.uk/wiki/doku.php?id=4_2:kb0009024. If <Modules> section exists in the web.config it must be removed.
IIS 8.5 must be configured with the following role features Web Server IIS roles required for IIS 8.5 Management Tools
iIS Management Compatibility IIS 6 Metabase Compatibility Web Server Common Http Features Default Document Directory Browsing HTTP Errors Static Content HTTP redirection Health and Diagnostics HTTP Logging Logging Tools Request Monitor Tracing Performance Static Content Compression Dynamic Content Compression Security Request Filtering Basic Authentication Client Certificate Mapping Authentication Windows Authentication Application Development .NET Extensibility 3.5 .NET Extensibility 4.5 ASP.NET 3.5 ASP.NET 4.5 ISAPI Extensions ISAPI Filters