I'm a fan of the Trijicon RMR on the Benelli. I usually go for the Trijicon RMR Type 2, RM09 which is a 1moa dot optic size. I see no purpose for the larger diameter dots since they just obstruct more of your target. I never found them to be faster than the small ones. With my eyes I can't tell the difference between the 1moa and the 3.5moa dot size.
For a mount, Scalarworks is what you seek.
https://scalarworks.com/shop/integral-mounts/sync-01/
https://www.amazon.com/Trijicon-RMR-Type-Adjustable-Sight/dp/B071XFFTJ8/ref=sr_1_1?dchild=1&keywords=trijicon+rmr+type+2+rm09&qid=1583982039&sr=8-1