Use `onBeforeSaveEntry` event to update EntryModel properties?
Just looking through the source file, it looks like sectionId, typeId, authorId, postDate and expiryDate are all set as properties on the $entryRecord before the onBeforeSaveUser event is fired. It also looks like $entryRecord is not accessible from the event, nor is it saved yet such that you could modify it directly. I suspect that you will need to modify these properties after the entry is saved (using the onSaveEntry event), and then resave the entry. You will also of course need to add conditionals (i.e. compare current authorId to target authorId) and only save the entry if needed, to ensure that you don't create an endless loop.