I'm a big fan of the Model 12, especially in 16 gauge, as it comes in with lightest receiver of them all and is a real bargain today. I'd look for a gun made in the mid/late '50s, as the stocks have a bit less drop and you don't have to worry about the short chamber issue (and all that goes with it).

Mine weighs 6 1/2# w/ 28" plain barrel, is one of the last guns I'd part with for any price.