I think Amazing Spider-Man, Vol. 6 #64H and 64I are duplicates and I’m not finding a missing variant.
First, the Megacon exclusive is a combined image of 63H and 64G. The barcode ends in 25. And the back cover says Megacon.
You can see this eBay listing for reference.
The existing 64H uses the same image as 63H. So I think you need the front image of 64I and the back cover and barcode from 64H.
Incidentally, the existing barcode and back cover of 64I are, I believe, duplicates of 64F.
When you’re done, I think there should be a trade and virgin of the left half (63G and 63H), a trade and virgin of the right half (64F and 64G) and then a Megacon exclusive with both halves (the image of 64I). I think that leaves an extra.
Thoughts? Thanks!