First of all, welcome! It's good to have you here and we look forward to hearing from you. I've been shooting Benelli shotguns since 1991, when I purchased my first SBE. I also have a Nova with a 24" barrel that I shoot on a regular basis.
Benelli barrels have very tight inside diameter bores and usually need a choke tube with exit diameters that are somewhat tighter than other 12 gauge shotguns. We regularly shoot Hevi-Shot products, including Hevi-13 turkey loads through chokes as tight as .640 - .650 with that gun with excellent results.
I recommend the SSX http://allaboutshooting.com/product_info.php?cPath=23&products_id=79
with your gun, especially since it has the 24" barrel like mine.
I would also recommend that you consider trying some of the 3" Hevi-13 "Bronze" shells with 2 oz. of #6 shot with your gun. Many times they pattern better than the 3.5" shells. They cost less and they certainly kick less.
The 3" Winchester Xtended Range Hi-Density shell with 1.75 oz. of #6 shot is also an excellent shell with your gun.
You can also get great patterns with the 3" Winchester HV (Black Shells) with 1.75 oz. of #6 lead shot with that combination.
Lastly, I'd recommend that you "deep clean" your barrel. Benelli barrels are chrome-lined and can look clean when in fact they have a lot of "gunk" in them that can negatively effect patterns. I'd recommend the article, "Cleaning a Shotgun Barrel" http://allaboutshooting.com/article_info.php?articles_id=282
and the guidelines there.
Best of luck this spring and if I can be of help, just let me know.