Honestly with the mileage that you have I STRONGLY recommend replacing the whole cooling system (minus the heater core) which you are close to doing anyway.

Replace radiator, all hoses, Tstat, waterpump and expansion tank.

These pieces all are weak at 100k and any one of them, including all 18 hoses, can quickly leave you stranded in the middle of no where...Trust me, it has happened to me.