Biggest most massive 4 core rad for a 68 Barracuda?

i have been running a 2 core and matching fan shroud out of a 85 chrysler 5th avenue with my 318in my duster, it fit perfect ,even the mounting holes are in the same spot ,and a 195 thermostat and ive tried repeatitly to get it hot and have had no luck. the best 30 bucks i ever spent.