Breech Plug:
Well young man, I can say that freely, because I'm over 70 yrs old, and judging from your responses you are considerably younger than that. I apologise that we were not able to provide you with the answere you wanted, but then again, we didn't know what you wanted to hear. We provide facts and not just wanted answers.
Mr. Farisweel has provided sound information. I fail to see how he or anyone else from this forum could make money by the information provided. Judging from his response he was trying 1) to save your well being and possibly your life by recommending the gun smith. My father, bless his soul, lost his thumb two fingers, not to mention the broken wrist of his left hand, from firing an old dbl bbl without having it looked at by a gun smith. 2) The gun smith would have a "hands on" approach and see the gun and be able to determine what grade Ithaca you have, and if it was safe to shoot. We cannot. Therefore the general ranges of value and condition can only be presented here.
In my humble opinion and Judging from what you describe, (markings etc) you Itaca is a "plain Jane" utillity grade. If there was engraving of some sort, this would up the grade. As Fariswheel pointed out Ithaca made a wide variety of grades and without seeing the gun no one here can determine what you have.
Additionally: I present the same advice regarding the "Smith". AND DON'T SHOOT IT WITHOUT HAVING IT CHECKED.
In the future, pay attention to detail in requesting information and refrain from attacking those who respond to you. We can provide only the ans. to the information provided by the requester. Should actions like this persist we will have to take another avenue of approach.
Harley