I really hate making magic items like I dislike making spell list. I simply cut and pasted S&W's magic items until I modified that one or the D20 system.
I decided that I am not making it a roll, only a choice.
The list is evergreen like the rest of the game.
It's going to be alot of Game Master Fiat. If fact almost everything about being a Game Master in Back to the Dungeon RPG will be very loose rules tempered by GM fiat. Ah yes such freedom!