64 273 new rebuild now with coolant in #6 (It's a Hybrid!)

Milkshake isn't horrible, but yes, oil will be drained! I'll pull the other head an clean off the copper crap and put on a new gasket just for peace of mind. Is there a better gasket I should use instead of the Fel-Pro 8553? or are they fine? This car is just a cruiser.