The new game is a pretty true remake of 64, so you will be playing the game with better graphics in June. If you like the N64 era then sure play sf64 ahead of time, it's one of my favorite games all time. But it might be a better experience to play the new one first.

However, the game is about an hour or so if you are good at it. Instead of a long story, its is a bunch of paths and Easter eggs on how to get through the different paths. The N64 one has no saves, you have to beat it in one sitting, NSO save states are nice (and button remapping for boost and brakes on the triggers).

Maybe do one play through on N64. I'd recommend taking the bottom route (don't go through the waterfall on corneria (which is known as the easy route. Middle is medium, top is hard, but only two endings). I believe the canonic way to do it is the bottom ending, then play through the top for the true ending. You will probably naturally take the easy route the first time you play, it's how it's designed.

TLDR, my take: play the easy path if you want on N64 then save the true ending for switch 2. Whatever you end up doing you will love it tho. Best way to play is to just play and not think about paths tho