Aftermarket aluminum radiators are available from Summit, JEGS, etc. You can also get, what are referred to as "factory-reproduction" units, but they are not that close to original, however many of them will install, using the factory lower & upper radiator saddles. You can get them from LMC Truck, Classic Parts, Truck & Car Shop, etc. Also, many of the fast-food variety auto parts stores, like O'Reilly, Advanced, etc, sell an aftermarket reproduction unit. They are also available from NAPA.
A good four core would be a good option, especially with a properly fitting shroud, or better yet, a high cfm electric fan, would be a good combination for keeping your 454 running cool.
Good luck and keep us posted on your bbc swap.
