Over heating questions

Hey guys so couple things. I have a 74 duster 318. I changed to a 3 core aluminum radiator but I am afraid that my car still runs too hot. I live in so cal so it does get pretty hot. First question whats a temperature that I should be worried about if it reaches. It usually runs about 160-210 depending on if I m moving and how hot it is. I have a 160 thermostat in it. Second question would upgrading to a 4 core make a difference. Comments suggestions and concerns are all welcome

Thanks,
Brian