Thank you for the replies. He can write a short sentence from dictation, or a longer one if I repeat it for him midway. Sometimes it's hard to get him to retell the 2 sentences verbally that I scribe for him. I know he knows the story, but he's anticipating having to write the sentences so doesn't want to tell me what to write.
He's good with the WWE copy work now, and will occasionally write 3 or 4 short sentences about a picture (getting to that point was a bear).
I wouldn't be so worried, except I may have to put him in public (or at least private) school in the fall, and don't want him to be considered behind in any way. With the exception or writing sentences, I am confident he is equal to or ahead of his grade in reading, phonics/spelling, math etc. ;)