Delving Deeper might just be your game.
Did I mention it's free in PDF?
Three booklets are in the release
The Adventurer's Handbook - which is where the classes reside
The Referee's Guide - where you find the rules for running the game
The Monster & Treasure Reference - where you find monsters and treasure. What, were you expecting a tricky type of answer? heh
You can grab all three together at the link above.
From the blurb:
What is the Delving Deeper RPG?
Delving Deeper is an emulation of the original fantasy role-playing game.
Meticulously forged over two long years of development, Delving Deeper invites you to recreate the original role-playing experience as it was in its earliest days.
Return to a time when three alignments were enough, when a handful of character classes ruled, and when magic swords had their own ideas about who's boss.
If you’ve ever read or watched a good fantasy with hungry eyes, then this is the game for you. Right here are all the rules you'll need, none of the rules you won't, and unparalleled room for expansion and growth. Grab your trusty sword, your magic wand, and call the guards to arms! There are treasures in these pages...