Cooling Issue - 1964 Dart GT - 273 with automatic and A/C

Does the new hose have a spring. It should have. If not, you can make one from welding wire, fencing wire or the humble wire coat hanger. Wrap wire around something a bit smaller in OD then the hose ID.
I would use a stainless wire and be sure it is a tight fix or it can end up in your water pump. I have gone to salvage yards in the past and pulled the wire out of an older vehicle and reused it in mine.