It would be a lot of work, for two reasons:

1) He would have to re-do all effects work that was originally done in SD from scratch

2) He'd have to rebuild the entire thing from scratch anyway, since Ady no longer has the original files, which is also why we'll never get a 480p high-bitrate mp4 or mkv.

I believe the files were lost when a hard drive failed, or Ady just deleted them because he thought he'd never need them again ... I don't remember to be honest.

So, while your file-replacement idea wouldn't be a bad one, it's just technically impossible since the original files no longer exist. He'd literally have to start everything over from scratch.

Not to mention he'd have to painstakingly, manually color-correct every shot ..... again.