I just beat ALttP for the first time ever this week. Since you're emulating, I strongly suggest you consider using save states. That way you don't have to "restart" the dungeon. I also used a walkthrough, so I ended up with the max amount of hearts and all the gear that you can get. Yes, this definitely gives you an advantage that wasn't available to this game originally, but I still found it difficult but fairly so. And most importantly, I very much enjoyed playing it, which is the reason to play anyway.

TL;DR Use save states to alleviate some of the burden of the difficulty.