Ubuntu Guest Shared Folder permissions - VirtualBox

I have mounted a folder from my Host machine (Win10) on my Ubuntu 15.10 guest. After using virtualbox dialogues to pair the folders I have placed the following mount dialogue in /etc/rc.local. It works, but the permissions within the shared folder are all set to chmod 777. I receive an "invalid mode" error when trying to set with "sudo chmod -R 755 */".

I'm aware that the mount command is blocking my attempts to change the permissions on the shared files, I just can't find the correct mount command to use to achieve chmod 755 permissions.

Any help would be appreciated.