Upgrading on Alitalia

Yes I searched for this first, but no I didn't find my answer completely.

Are my SWUs worthless on Alitalia?

I want to upgrade from Premium Economy JFK-FCO to Biz. What is the best way to do this and what routes have the best J product?

I have a hoard of Amex MR points sitting around so those are a possibility too I guess...

Thanks everyone