If you’re going that way, I would probably start with a single set like Alpha/Beta/Unlimited or a core set and just make the spells from that.I was hoping to retainer magic cards as spells rather than using another system, but I'm having a hard time finding a concise list as there's so many damn magic cards now.
Yeah, you could stick with instants and sorceries (interrupts haven’t been a thing for a long time, all the original interrupts have long been errata’d to instants), and have artifacts be magic items, creatures be monsters, etc. Not exactly sure what you’d want to do about enchantments.I'm thinking that most spells need to be found in instants, interrupts and sorceries. But even these have a super heavy focus on creatures and summons.
EDIT: The difference could be casting time and duration. Instants have a 1-action or reaction cast time and instantaneous duration, Sorceries have cast times in minutes and instantaneous duration, enchantments have cast times in minutes and durations that last a longer time.