I would imigine the Canadian C7 family is like the M16A2 family, with a nice big triangluar bump on the upper reciever behind the ejection port, they work just fine for lefties.
I'm right handed but shoot left handed most of the time.
One weapon for ALL, no need for left-handed - right handed. What needs to be done is training to make all soldiers shoot left or right handed just as equally. Or at least acceptable on weak side.
Not to mention the odd chance one is wounded, that hever happens right? one can't just give up and stop firing in some circumstances.
There are many times one will need the ability to fire from behind cover that will only allow left or right handed shots. Think about it for a few minutes. I think all will agree a highly vaulable ability once learned.