Are you sure it's not just the bottom hose? They get weak and collapse. Find one with a wire coil inside it, or for a "farmer fix" to see if it's the problem, put a few hose clamps on it to keep it round, and test drive it. Or wrap some heavy wire around it to do the same thing.
I put a '55 Chev rad in my '54 when I put in a 283, bolted right in but a little shorter and thicker.