Like him or hate him, +Venger Satanis does has released some extremely competent OSR releases. The S'rulyan Vault is definitely on the top of the Venger release list.
Until 11 AM Eastern, tomorrow August 29th, 2016 The S'rulyan Vault is discounted 40% in PDF, from $7 to $4.2o.
From the blurb:
This product is both a PDF and very large, high resolution map files.
The PDF contains a short history of the region and dungeon, original artwork by Bojan Sucevic, and several random tables for making this dungeoncrawl easier to run and more interesting. For instance, there's a d100 table describing things found when searching a room. There's also a multi-table system for generating fortunes.
Lastly, there's a custom, old school fantasy character sheet created by James V West.
As for the maps, there's an old school blue and white layout of the dungeon... just like we remember from the modules in the late 70's and early 80's. Alternatively, there's a parchment colored map. Each one can be taken to a printer and blown up to 34" x 44".