You could also try a really old Rapid Rectillinear. Believe it or not I had a Montgomery Ward RR (c. 1897) that had the exact look you're describing (example: http://www.redhillphoto.com/portfoli...andoah8102.jpg - it's an 8x10, but a RR with a shorter focal length might be what you'd like). If you get something that covers 8x10, the "sweet spot" might be entirely encompass 4x5, which would kind of negate the effect you're looking for.