This is an interesting question to me because I have never seen a JPEG image where the meta information comes after the image data. It shouldn't happen.

By convention, in a JPEG image the IPTC meta information is stored within the Photoshop IRB records inside the JPEG APP13 segment. By the EXIF specification, the EXIF APP1 segment should come first in the image, then typically the APP13 segment comes next. I have sometimes seen Photoshop files where the APP13 segment comes first, but this is incorrect and ExifTool will not write an image like this. In either case though, both APP1 and APP13 come before the image data. In fact, for speed ExifTool does not even parse an image beyond the SOI (Start Of Image) marker when extracting information.

The XMP information is stored in a second APP1 segment, which ExifTool writes after the Photoshop APP13 segment, but other utilities may write the APP segments in a different order. This is fine, as long as the EXIF APP1 segment comes first and they all come before the SOI.

The IPTC Application version has nothing to do with where the information is stored.

Perhaps a sample would be useful so I can see what you are talking about. Also, why do you care about where the information is stored?