They will not be able to survive in the temps that tropicals require. It's going to be really hard on their immune systems. And two common goldfish will get far too big for a 60 gallon, especially if other tank-mates are present. In all reality two common golds need 75-100G of over-filtered water (not heated) to be happy and healthy.
Stick with other tropical community fish in your 60 gallon and you will have a much healthier tank.