Heater core isn’t fitting in Plymouth Duster

The two pipes that go through the firewall and into the engine bay do not fit into the grove underneath the dash. One of the pipes is bent in such a way that it is impossible to work. I’ve already broken the pipe once trying to bend it in place and I had to take it to a radiator shop to get it welded. It is the correct part. Has anyone ran into this problem before and what do yoy’all guys suggest to do to get it fixed? It’s a 1976 Plymouth Duster without AC.