I've been thinking again about adversity rolls, also known as System Shock or Resurrection Survival rolls in later editions. I'm dead-set against percentile rolls in Liber Zero, since they stick out when surrounded by the d20 and d6-based rolls that are standard in the original edition. This would make the natural replacement either a Target 20 roll that is not modified by level or some kind of d6-based roll. The Target 20 roll would be a little weird if I tried to keep it close to the results indicated by the notes on Constitution in Men & Magic, since you'd have to add 2 x (Con -5), not exactly a typical formula for simple, old-school play. I suggested a 2d6 roll <= Con, which works better, but it also adds a new type of resolution roll to the game, one that doesn't crop up very often. So I've been thinking about two choices that are simultaneously more radical and more traditional.
Option 1: make it a "Reaction to Adversity" roll. Use a standard 2d6 reaction roll to describe how intact the body is after days of decay (or years of erosion, for petrification.) A Very Hostile/Very Low result means the body suffered too much damage to be restored to life. If the character has Low Constitution, there's a -1 penalty, double for Very Low, triple for Extremely Low; High Con means a bonus instead of a penalty. Maybe even throw in a penalty for each week a corpse has been dead, or each decade of petrification, just to keep the Very High Con people from feeling invulnerable.
Option 2: go with the tried-and-true Situation Roll. When attempting to restore life to a dead or petrified character, roll 1d6 to see if the corpse avoids accidental damage (4 or less;) add +1 difficulty to the roll if the character's Con is Low, +2 if Very Low; High Con adds +1 to the target number.
There are downsides to each choice, of course. But which solution seems to be the simplest? Which is closer in spirit or in feel to the original?