The 'key word' in your post that adds a lot of difficulty is 'correctly'... For a '69 Z28 radiator, I was unable to find ANY shop anywhere that could obtain 'correct' cores. What was necessary was to disassemble my original radiator and send the top and bottom rails to the company to USE in building a replacement radiator core, and then a radiator shop can install it into your tanks and brackets... This makes it very complicated, and more costly and time consuming to get the radiator 'correctly' recored...