Which radiator?

I’m coming back around to this topic. I’m running a 340 in my 1965 dart. My question is how do I choose a radiator? Seeing that the engine is Mis-matched with the car. currently my lower radiator hose comes out on the passenger side and hooks up to the passenger side. Also the current radiator I have has an external transmission cooler and I know the newer ones have internal. Is that going to make a difference? Transmission is a 904LA. Water pump is a high flow pump. Looking for a good functioning/cooling radiator but that is also budget friendly.