If you're going with a new radiator, I'd go with something like the one in the link below. Two row aluminum radiators actually cool better than a three row radiator given the same thickness.
The big block Mopar includes a range of displacements from 383 to well over 500 cubes in modern crate motor incarnations. Hemi motors are also included in this category of engines. In most builds, the radiator is one of the last thing most guys purchase. Only to find they have some major...
ecp-radiator.com
If you want to keep your current hose routing, get the small block version.
26″ Small Block Mopar Radiator This it our all new aluminum radiator for the 1967 - 1974 Mopar Small Block Cars that use the 26" large radiator. Like all of our radiators, it's made with proven 2-rows of 1.0" tubes that is proven to out cool 3-row and 4-row aluminum radiators by a substantial...
ecp-radiator.com