So in theory you could wait 800 hours to become but honestly at that point you won't have much con left to enjoy the perks of mummy/lichdom.

Also the anticipation would suck. I got the mummy quest down to a fine science (70-80% chance on each attempt) and the hours required for that were 240. So going to 600-800 as a scpectre would be a living hell.

Maybe I'll publish that howto if they continue to discriminate against PETM members of Slavic origin.