I don't really see undead increasing their health through constitution as making any more or less sense than living creatures. I mean, how can a human get hit by 2 sword attacks at level 1, and 10 at level 12? The way I see it with undead is constitution would basically increase their vitality, their connection to life itself. You can take more physical blows because you have greater willpower.
Wonder if Undead will basically have zombie talent by default, where poison heals and healing hurts? And then maybe a special ability like "Channel Life," that lets you temporarily reverse that, or just let you get healed by regular healing.
Plus crushing vulnerability and slashing resist, if it is more of a skeleton. Necromantic source power for raising dead would be cool.
