Great research.
So if this is Aristarchus' model as to the sizes:
What do we think about whether Epicurus was disputing this, or whether is "it is the size it appears to be" can be reconciled with this, which would indicate that the sun is larger than the earth?
It could not have been lost on Epicurus that as formula in words like "it is the size it appears to be" will strike some people as too ambiguous to be useful. So is that phrasing in itself an indication that Epicurus knew very well that the sun was not the size of an orange or any everyday object like people accuse him of believing? Almost certainly he knew that a very large size was a reasonable possibility, and it doesn't appear that he wanted to eliminate that possibility, along the lines of our continuing observation that only one among several alternate possibilities can't be arbitrarily selected as the sole answer.
Maybe that's an easier way to ask the question.
"Does Epicurus' answer allow for the possibility of the Sun being larger than the earth?"