I put on a weaver base and it works good. I was thinking of putting on Millet rings but I seen some Leupold QR on a GG today at the gun shop and the QR option seems like someting to concider. the scope I'm mounting is a 4x Leupold Compact.
XS Lever rail with the ghost ring back up sights is what is on my 1895GS, I liked the ghost rings so much I have yet to put a scope on it. If I were to put a scope on it, it would be a scout scope for sure. The long rail set up allows you to mount either scout scope or traditional scope.