How old was Gilgamesh when he died? [Fate/Go]

After thinking about the Babylonia singularity, I started to wonder how exactly did Gilgamesh die of overwork since his mana reserves allowed him to both comfortably spar with you while maintaining all his servants and he lost a few servants between that moment and the moment he died, which should have significantly lessened his mana drain. Now I'm wondering if the real reason Gilgamesh died in the story was actually old age since they never really mention how long it took him to take the journey of immortality and come back and it could explain why his attitude is so drastically different. So how old do you think Gilgamesh was in Fate before he died?