Over heating 429

First time here. . Does anyone know what size water pump pulley should be on a 1973 429 ? I had the engine rebuilt but it didn't have a pulley on it. I installed a after market billet pulley kit . Engine is installed in a kit car but am having over heating problems , was told wrong pulley size could be problem . Makes sense. .

Don't know the stock size, but if you don't move enough water at Idle and low speed your motor will over heat quickly. The larger the lower pulley the faster it will turn the belt.