Radiator Install Help!

[Goinlow64]

I have a champion radiator I am trying to put in my 64 with a 350/350 combo. When I mocked it up, I found the radiator did not sit in the factory retainers. It was too wide to fit between the frame. The only place it could really fit is on top of the frame. However, it looks like the top of the radiator is about where it should be.

This is my first build and I am a little lost. Do I just not use the factory retainers in between the frame? Or do I have the wrong radiator. The core itself lines up perfect with the core support when sitting on top of the frame.

If I do bypass the factory retainer, how do I mount it? Thanks for your answers!