That is close enough.
From the manual.
Upload all files and directories from the unzipped UBBâ„¢ directory to the UBBâ„¢ installation directory, except for the includes, styles, and cache_builders/custom directories. You will want to upload all of the .php files within the cache_builders directory, just make sure not to upload the custom directory or files within it.
The reason behind this is that you don't overwrite a file that has been changed by you.
Usually with a existing board you will not need to change file/folder permissions unless it is a net new item.
But with your case it should be okay.But it does not hurt to check anyway.
Also there are no files to delete other than the install folder when complete. This is so some bad person that knows the software structure will not run the install or upgrade scripts and hose your board.
GO FOR IT!!
DON"T FORGET TO MAKE A BACKUP FIRST.
