What is the proper radiator for my truck?

[tylers71c20]

Hi all i have a 1971 chevy c-20 pick up. i just put in a brandnew chevy 350 out of a 72 montecalro. i have a turbo 350 tranny to go along with it, but my radiator is wrong. the tranny cooling lines dont match up and it dosent cool the engine right. i would like to know exaclty what radiator i need, so i dont have to ask some shop owner and they just sell me what ever they have in stock. i would like to just tell the guy this is what i need and do you have it?
ANY help is very much appreciated! and dont be afraid to ask me anymore details about the truck so you can give me a correct answer.

Thanks alot!

Tyler (young buck from upstate NY)