This thread seems as good a place as any to ask: what is a great adventure for running in AD&D 2E from the OSR? I am looking for something in the 4th to 7th level range that could last maybe a half dozen sessions.
ETA for clarity: I would be using just the core books for AD&D 2E, not the splats or Skills and Powers.
So a few things...
A) 2E will work, but you may have to do a few adaptive tweaks, most OSR adventures are written in a variety of house ruled formats that while broadly compatible with 2E will not be close to the stat blocks and such. It should be pretty easy.
B) Levels 4-7, have not been especially popular for OSR releases, and especially in the late-OSR period and the present are fairly rare as published work from the OSR tends toward levels 1-3 for a variety of reasons.
Not knowing exactly what you want or what sort of design ethos is your fave I'd suggest looking at the following.
For "High OSR" - or the period when early forum OSR started to be less concerned about retro-clones and the blog OSR was really blooming the best published stuff was Mega Dungeons.
Stonehell's lower levels are level 4-7 I think. Likewise maybe take a look at the
ASE - it gets close level range in Book 2.
For Mid-OSR (G+ OSR and blog OSR ... the Renaissance) I think
Deep Carbon Observatory is still your best bet. It's not, not levels 4-7 but it's more a set of puzzles and vibes then a careful balanced crawl. It is also very much of that era and space.
Not sure what to recommend for late OSR at those levels. Most of the stuff I know of that era is low level. Maybe
Lorn Song of the Bachelor by Zedek Sew, though you would like have to pump up the power of the Bachelor (a giant crocodile), village chief and a few other things. It's a solid late OSR adventure, but it tends towards ultralight style play and bends under a proceduralist approach. Great factions, ideas and writing though.
For a step to the modern Old School Revival (that is the continued impulses of Forum/Revivalist OSR and specifically the AD&D side of things) Anthony Huso's work is well regarded. He's sort of a unique auteur type dealing in a system and set of tones that aren't super "of the moment", but he does his own thing very well and I have nothing but good things to say. The old games space needs more people doing their own thing.
Now - as others have suggested, old games with old adventures are worthwhile. I think Jaquays'
Dark Tower is Level 4-7 and it's great. Not as good as Thracia, but nice and an example of her design style. Likewise
Steading of the Hill Giant Chief (G1) - Gygax wrote a great open ended problem there - a siege/infiltration scenario that captures a certain open to hijinxs feel. It's not detailed like a Jaquay's dungeon or beautifully written (DCO is my bet for that) but it's a good adventure - especially for the late 1970's. You could always try
Tomb of Horrors as well...but only if your players really like puzzles, annoying ones.
Personally I think my own
Tomb Robbers of the Crystal Frontier is the best OSR adventure of the past 3 years - but it's a level 1-3 and also this is partially vanity. For intros I like Arnold's
Lair of the Lamb and my own
Prison of the Hated Pretender ... but again these are 0-1 level one shots (Prison is specifically designed as a one session thing - but that doesn't always work). Honestly I think there are some issues with mid-level adventures if one wants to write an exploration focused dungeon crawl (it's something I'm working on personally but it's a tough nut) due to the various tools that the Greyhawk campaign injected to deal with exploration challenge and the way combat works in early D&Ds at mid-level.
