I'm not sure who makes one anymore, if anyone, but a straight 2 3/4x scope I would think would be just the ticket. You might be able to find a 1x4x if you want a variable but for what your talking a 2 3/4x would wokr really well. I have one I bought new about 1970, it's not for sale!

Two other scopes I would highly recommend for a shotgun are the Leupold European 30mm in either 1.25-4x20 or 2-7x33. Both these scopes have superior eye relief and also seem to be very easy to line up behind; a good "eyebox", if you will. 

I have the lower powered one mounted on a BLR in .450 now and it's simply a match made in heaven. The 2-7 is mounted on another BLR in .325WSM. I have been very happy with the overall performance of both. It's becoming tough to find Zeiss Conquest scopes in the lower power ranges now (my two low powered ones were bought from Cabela's on closeout) and my wallet begins to hide when prices rise above the Conquest line. I know the pricier 30mm Zeiss series are also better scopes, I just haven't been able to go there.