Yes, I have booked a similar ticket on continental (z fare) from BWI to SNA but the actual flight was UA metal. Although, its a discounted business class fare, my seats were in F cabin mainly because the flights had only two cabins. There was no biz cabin.
In your case, since you are fliying transatlantic, you might actually end up in a 3 cabin flight and get a seat in biz cabin.
But the it works.
So, enjoy the cheaper fare while it lasts.