Bill - Benelli has the Montefeltro Youth. This is what my 8year-old shoots. If I remeber correctly, the Monty Youth has the shortest LoP of any AL youth gun, comes with shims to adjust fit, and accepts the full size stock when they get big. The Beretta 391 Youth's LoP is just a little longer, a little heavier, and is a gas gun, but probably the best gas shotgun out there (except for my M4:D), while I would argue the Monty is the best shotgun overall due to its simplicity.
Both guns are great (as are the Remington 1100 and 1187 youths). The 391 being gas instead of Inertia Drive, it will get a little dirtier than the Monty.
Recoil will most likely be lighter with the heavier gas guns, but can also be managed with modified loads. My son started out with 5/8oz then 3/4oz and now factory 7/8oz without complaining. The biggest piece of advice I can offer is get something that fits her and she is comfortable handling, then you can then adjust the loads to her recoil tolerance. It has been my experience with kids, light recoil in a gun that is awkward will turn them off just as much as heavy recoil.
Good luck and safe shooting!!