I would have the remake on WiiWare.

I would really pump up the production value sound and visuals. have an art style simlair to Twilight Princess to match the hard core difficulty. It would be a 3-D side scroller like Viewtul Joe

offer some new play mechanics like new spells and items to use in and out of battle. But not change it too much.

It would still have the ball busting hard difficulty of the original but more fair like haveing you at the dungeon entrance instead of all the way back at the start when you lose all lives.

add maps and compasses to help the player not get lost.

maybe add some cutscenes with side quests like when Link had to save a kid from a Lizafos to give some story depth and make sure the final battle with Dark Link is the best moment in the game.

then top it all with hidden treasures, easter eggs, minigames, maybe an extra optional dungeon or two.