There are numerous models dating from 1891. And since these were made by Italians and not Germans, the model names and variations are some what vague. The rifles were not marked to indicate models. Collectors have since agreed upon what to call the different variants but they do not match anything in Italy. Depending on what you have, the price may vary.
Also, depending on what has been done to yours, the price may vary. If only the stock has been altered, then the value would be higher than one that has missing parts, drilled and tapped receiver and cut barrel. As Martin has stated, stocks for these are difficult to find but not impossible. The question is whether it is worth it.
Pictures of your gun would be great and we can tell you a lot more about it. Here is a good website describing the variants.
The ITALIAN CARCANO RIFLE
Each gun was marked with the arsenal which was sometimes just letters, the year it was made using the normal way and then again using Roman numerals to indicate the year of IL Duce's reign, and a serail number in addition to the caliber. If you post pics make sure to get some of the markings.
As far as how good they were that of course is a matter of opinion. These were not Mausers. Their design and quality could not compete with Mauser, but made good enough for their purpose. (Much like the Mosins). In the hands of a trained soldier they were as good as any rifle in WWII for killing the enemy.
As far as the Kennedy rifle, that was a Model 1891/38 which was the most numerous carbine. It was altered by Klein's Sporting Goods in Chicago by using a stamped side mounted scope mount and a very very cheap Japanese scope. I once owned one from Klein's exactly like Oswalds in every detail, even the arsenal and year made, and recreated the shot the best I could. IMHO, the rifle with iron sights was easily up to the job. The scope was not, but since it was side mounted, the iron sights were usable.
It would be great to see pics if you get the chance.