The Buster Gundam, which reappeared in SEED FREEDOM, has also received an updated kit.

I compared the old HG Buster with the new Lightning Buster. While the exterior design is almost identical except for the weapons, the renewal gives it a much sleeker, more modern proportion. Looking at it this way, the old HG, while feeling dated, had decent proportions.

If you wanted to, you could probably create a renewed version of the Buster by using the Lightning Buster as a base and modifying/transferring weapons from the original Buster... but along with the Duel Assault Shroud, that would definitely be a long shot.

HG Buster Gundam old vs new comparison | shin's Gunpla works