All modern large aircraft (as far as I know) use turbine engines (jet or turboprop).  What's the largest aircraft that's still flying that uses AvGas (or, rather, has radial IC engines)?  I know there are still plenty of DC-3s that fly regularly, but is there anything larger that's still in use?

If it makes a difference, by "largest" I mean "heaviest", and by "in use" I mean "flies at least annually" - the Spruce Goose is, I believe, technically airworthy, but it's not flown since 1947.