Even with pictures it is impossible to tell if a gun is safe to shoot. You need to bring it to a gunsmith who is familiar with SxS's. He needs to be experienced.
Dave M has it right. From the description without pictures that is about as close as someone can get to its value. It is a lower grade gun from your description. Condition and how much it is original will be the factors that set its value.
Twist steel can be safe to shoot but not without being checked by a competent gunsmith.
In my opinion, the lifter action is far more user friendly than a top lever. The last ones built were probably in the early 1880's. I don't know if they are as strong as a top lever. Others may chime in. I love mine and prefer the underlifter to top lever.
