The Tales from the Yawning Portal features 7 adventures that were "upgraded" from older editions. One of them is the famous Tomb of Horrors.
Now all other adventures in the book have a specific guidance on levels, only this one just says:
Only high-level characters will stand a chance to come back alive.
The old cover ("Dungeon Module S1") read
An adventure for characters level 10-14
So to keep the deadly experience, what is a good, "high-level" level? And how many characters are expected? The module certainly has a lot of level-dependent challenges. It has monsters, DCs, hit point damage. Is 10-14 in D&D 5 appropriate to keep the original, deadly experience?