Rad hoses.

I used '68 Coronet 383 for the upper with that configuration. I believe the lower I used was factory big block A-body, but I'd have to search it out to be sure.
Factory big block A body hoses will work if the radiator ports are in the factory location. With a custom aluminum radiator the ports could be anywhere. If the ports aren't in the factory location then none of us can help since we have no idea which hose will work.