water pump pully size

whats the good pully size ratio between the water pump and crank for a near stocksmall block, i am thinking 1-1. my car starts to creep up over 70mph on hot days. its got a decent 3 core radiator hood to radiator seal and fan shroud. i noticed my water pump pully is almost one inch bigger than the crank and that mite be a factor. its a 340 67 barracuda stock size radiator