I wouldn't do it. Repeated steel shooting can damage the choke. Do you know where the shotgun is choked? Modified, Improved, Full? I've got a mid 50's Remington pump and will only use lead. Just not worth ruining a vintage weapon.
I'd say 7 shots in a 2" at 30 yards is very adequite. I know that 2 or 3 at 50+ yards will bring down a goose.