Pancetta in MSP?
They'll slice it to order for you at Cossetta's in downtown St. Paul or Buon Giorno in Lilydale. There's also Delmonico's in NE Minneapolis, but I haven't bought meat there.
Delmonico's Italian Foods
1112 Summer St Ne, Minneapolis, MN
981 sibley memorial hwy, Lilydale, MN 55118
Cossetta Italian Market-Pizzeria
211 7th St, W St Paul, MN
I'd call Delmonico's before going there - I am not sure they have pancetta.
I've only bought it from Kowalski's, which sells it rolled.
The rolled pancetta isn't inauthentic. It's sold that way in Italy. In the UK, it's sold in strips, but it's an Italian in origin. The question is in the quality of the meat rather than strips or rolls - unless, as I suspect is the case for the OP, it's needed a particular way for a recipe.
Clancey's makes their own but it is usually rolled. Since is not packaged in that form, only tied after curing it should be pretty easy to straighten it out. If you are buying in any real quantity you could probably special order one.
Clancey's Meats & Fish
4307 Upton Ave S, Minneapolis, MN 55410