I used a Volare (slant six) radiator in my '64 (225, 904) for several years after the original ('64) radiator tanks rotted out. Mounting just took a couple of holes drilled in the wide flange on the radiator. In my car it required a non-lever radiator cap for hood clearance, and a Volare lower hose. I must have inadvertently ordered the non-HD or non-AC version, because it was barely adequate in the Texas summer even before I put AC back in the car.
Now I'm running an American Eagle aluminum radiator intended for a 289 automatic '67 Mustang. The lower hose is different in diameter and is a little wrong in position, and the one of the transmission cooler outlets is aimed at the harmonic balancer. It took some not-so-pretty rigging to get it moved over a little, and to make the lines clear. This is a two-row (1" tubes) unit, which leaves no room for the factory fan. I have one pusher fan up front, and would like to add another. This setup is not pretty but it cools very well even with the AC on. I can't really recommend that approach.
I read somewhere that Champion will move the outlet on a V8 A-body radiator to the passenger side. Might give them a call.
