i would strongly recommend replacing your stock radiator and upgrading the cooling system.
the stock radiator is tiny and satisfactory for cooling a /6, not a small block. even lowly 273 2bbls got a bigger radiator. also, the inlet and outlet will be in totally the wrong place (potentially), and that makes it a giant pain in the dick to get the radiator hoses right and generally you'll just wind up with some cobbled together mess of cut up elbows, lengths of pipe and a dumb accordion looking hose trying to make it all work.
so much easier to roll into the parts store and say i need a upper radiator hose for [blank] and not only do they have it, but it fits.