The '71 Charger with 500" stroker is still running the stock 26" radiator with the Mopar Performance viscous fan package. I also have a pusher fan in front of the radiator, but mostly use it in the pits to cool the radiator with the engine off. Although this works, it is on the edge, and it temps do creep up on long drives when it is 90+ degrees out.
My '69 Coronet 505" stroker had a Champion 26" 4-core radiator. Pretty good for the cost. With Mopar Performance viscous fan package, no problem cooling. With the Contour (Ford) dual cooling fans replacing mechanical fan, it still cooled good until I added A/C and the A/C condenser in front of the radiator. The extra heat load and reduced air flow from the A/C setup made that combination marginal in hot weather. I think mostly airflow related. I have switched to the Griffin Exact Fit radiator and Larger Spal 13" dual fans. I hope it cools better, but I have made other changes and have not driven the car with that setup yet.
I also had a GlenRay HD Radiator with the mechanical setup, and it worked great, but when switching to the electric fan setup I did not want to mess up that radiator so I set it aside and installed the Champion.
On the Champion radiators, I think in my setup the 3-core may have cooled as well or better than the 4-core because the 4-core is pretty thick and I think that partly reduced the air-flow through the radiator.