[Claressa]

I read that heating to 120 degrees for 24 hrs will kill the spores

That means keeping the temperature of the honey at 120 degrees for 24 hrs, not just heating it that long. It may take you up to 48 hours to achieve a constant sporicidal temperature. Even then, spores are incredibly resistant to heat, dessication, and irradiation. Personally, I would eat the honey and feed the new bees some nice clean syrup.