[DM] Could I get some suggestions on this dungeon idea?

Okay, so I’m new to AD&D 1e as a DM and so far we’ve done some test scenarios for combat and it seems like everything teeters close TPK when the party is 1st level. I’m planning my first full dungeon delve for them as a sort of primer into the campaign proper. I’ve got an idea of having them go giant ant hunting and uncovering a lost religious manuscript that has revelation type vibes. I want to give them a good challenge, but I don’t want to TPK them. So, I’m looking for some advice.

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The Party

2 PCs: 1 Magic-User, 1 Assassin

2 Henchmen: 1 Cleric, 1 Thief

1 War Dog

The players control their henchmen and the magic-user controls her war dog. They are all 1st level.

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The Dungeon

Total of 7 floors.

(1)Abandoned church: 5 Workers, 1 Warrior

(2) First level of colony: 6 workers, 1 warrior

(3) Second level of colony: 5 workers, 1 warrior (treasure cache)

(4) Third level:3 workers (treasure cache)

(5) Fourth level: 3 workers, 1 warrior

(6) Fifth level: 5 workers, 1 warrior

(7) Queen’s Chamber: 10 workers, 2 warriors (2 treasure caches)

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Workers: 2 hit die, AC 3, 1-6 damage, move 18

Warriors: 3 hit die, AC 3, 2-8 damage (3-12 poison sting on hit), Move: 18

Queen: 10 hit die, AC 3, no attacks or movement

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So, tweaks or suggestions? Is this balanced for 4 1st level characters + 1 beast?

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Thanks for all the help!!! You’ve given some great advice. We’re running the dungeon tonight and I’ll post an update on how it all went. (When I post the update I’ll also include the dungeon in a fancy PDF write up for others to use,)