1320 for an 8th grader. Is this considered good? What can I expect for a score in 11th grade or converting to a SAT score?
This is a little bit like those questions “My index score is 224. Do you think I have a chance to make the cutoff in Wyomng?” Um, yes. pretty good chance. 
Your 8th grader did EXCEPTIONALLY WELL. My guess is that he/she will score in the 1500 range in a few years.
Thanks so much @mnpapa29