I've been shotgunning for over 20 years.
If you have the some cash to blow. Get professionally fit, so you know your exacting length of pull.
Does your SBE have shims already in behind the butt pad or where the stock affixes to the receiver? If so, trying removing some. You may be able to get a shorter stock from Benelli for a reasonable price.
Some Benellis have recoil reducing hardware/devices in the stock. You need to see a schematic with measurements before you cut(if you cut it), obviously. I would start with sending Benelli an email.
Benelli is making 3 different thickness of butt pads for some of there guns, maybe 1 of these would work on your SBE. Also one of my SBE's had a black plastic slim between the pad and the stock that I removed when I put on a LimbSaver pad, this might shorten things up a bit.