65 Dart/Big Block/Cooling

Hi, I'm Jim, new to this thread and building a 65 Dart GT, Big Block 400, RMS AlterKtion/Street Lynx, Moser 9", etc...
Awaiting shift and kick down cables (ordered).
Going to rewire, Painless Harness/Kit.
Get the AC to work
Finish plumbing the brakes and fuel this week.

Looking for Tech Advise on cooling 450hp in the very, limited space available. I'm probably overthinking this a bit but... I started looking at radiators that will fit the Dart Core Support opening. with the belt driven pump and a fan, I have 5" from the fan mounting surface to the humps in the core support (radiator flange mounts). Install one of the available radiators and a fan and it's close, really close, on the tape. So I ordered an electric pump and gained about a 1/2", now I need a radiator and electric fan(s) to fit and provide adequate cooling... Looking for Ideas, Recommendations, Experiences.