It's Just My Opinion, but if your old rad wasn't flowing like it should, a new one would be a big improvement. I would think that a new stock radiator with a fan shroud or a good electric fan should give you adequate cooling.
If you want aluminum, then get aluminum....but I don't think it would be necessary.
You said you wanted better than stock....I guess I'm saying that stock working like it should would probably be somewhat better than the 'stock' you have experienced.