What should the party level be for this converted 1e dungeon?

I started my GREYHAWK campaign with the intro module Village of Hommlet starting at level 1.

In case you don't know, Goodman Games released a 5E converted version of Temple of Elemental Evil as part of their Original Adventures Reincarnated product line.

Based on what I recall of the original, they need to be level 8 to start, average 9.

I think it will depend on the conversion. 5e characters are a lot more durable than 1e and the monster stats are different.

The Goodman Games version appears to be designed for level 1-7 while the Classic Modules Today version on their website lists T1-4 as levels 1-8. So, starting at level 8 may require you to boost encounters in the conversions to match the player levels.

On the other hand, you could grab official 5e conversions from Tales from the Yawning Portal or Ghosts of Saltmarsh or use new content from Candlekeep Mysteries,  Keys from the Golden Vault or Radiant Citadel to string some modules together into a campaign.

P.S. CoS has enough leveling milestones for the characters to be level 12-14 by the end - which would be a bit high for the ToEE conversions mentioned. If you try to keep them at a lower level in CoS then they could have some difficulty with Strahd depending on how you want to run it.

Quote from Eldritch_Queen >>

I'm aware of the Goodman Games version. However, I already bought the Classic Modules Today version, so I'm going to use that.

In any case, what was the average level of your party/players when they eventually got to the temple?

 I didn't run the Temple of Elemental Evil, my GREYHAWK campaign was sandbox with my own adventures and only used T1:Village of Hommlet to start it.

The Goodman Games 5E Temple of Elemental Evil  is level 1-7 while the original TSR 1E Temple of Elemental Evil  was level 1-8.