Is is normal for a full int cleric have only 1.1k hp? having a hard time to fight the really old, especially when he summoned taurus...
That sounds pretty regular. I don't remember the fight being that difficult even without good gear. Just make sure you magic guard and kite him out with teleport and I think you should be fine.
I remember it was nearly impossible to attack the clone without killing the taurus. Prepare enough all cure potion or holy water and you should be fine!