Hmmm, basil leaves for wrapping . . .that sounds interesting, actually.

where can I get or buy seeds for giant basil?

Johnny's sells a couple of the lettuce leaf varieties, as does Pinetree. With no effort, you will be getting leaves that are 4-6 inches long. If you give the plant lots of room, fertilizer and water, the leaves will be bigger.

growitalian.com sells a great-tasting variety called Napoletano which has better flavor than any other lettuce leaf's I've tried.