Are new aluminum radiators better?

Aluminum is actually far better at thermal transfer than brass.

Brass vs. Aluminum: Radiator Thermal Properties

OP, run aluminum if you're not on the OE/Resto kick.
And a good sacrificial anode won't hurt, either.
Mopar Radiators these guys here have what seem like the perfect fit, but its 67 mopar....no where can i find 66 dodge dart at least with what seems like a reliable brand. Can i put the 67 on my 66?