(I tried posting this reply already, but I don't think it went through. Apologies in advance for any duplications.)
Hi. I read your note , but I'm afraid I am not really finding much. This VanSciver book is not the best, as the author didn't dwell much on people not in her direct line.
There are a few Elizabeth VanScivers listed, and one who is in the index as Elizabeth Ann VanSciver, but she doesn't appear to be the right one.
This Elizabeth Ann was the daughter of Charles Van Sciver and his wife, Lydia. She was born on Sept 17, 1813 and died on March 25, 1870.Her siblings were William, George, Emmaline and MaryAnn.
In the index, the next page which refers to Elizabeth Ann is actually a different one.Elizabeth Ann Buzby married George W. VanSciver. So she * became* a Van Sciver, but is listed in the index as if she were the one mentioned above.
None of the other Elizabeths mentioned seem to be the one you are looking for. There is an index of surnames for people who married Van Scivers, but Long is not among those listed.