In this hack, players pick polyhedral dice for each Attribute, making sure the highest sum is exactly 42. Next, a class is selected, with each having proficiencies and a pair of die boosting powers. One power grants the next size up for rolling, the other contributes a bonus D4 or D6. Rather than make a host of hit tables, combat employs basic opposed attack and defence rolls. The latter uses base speed instead of an attribute, so a PC can't max himself into a super-ninja.
With OSR spells already 90% sorted into schools, the task of making casters unique is easy. My bard-like Minstrel has a much different play style than a specialized Wizard, and captures that type of "niche sub-class" focus that Pathfinder extols. Instead of levels, magic is sorted into Minor, Lesser, and Greater incantations. I did this for another game of mine and it reduces some weight.