As said don't throw the old one, may just need flushing, the power of the car dosen't matter, the alloy one you have though will just dissipate heat better due to the material being a better conductor of heat, a bonus is it's also lighter!
Don't fit the terrible standard switch to the alloy rad as it suffers a heatsink effect and your fans won't turn off once they come on! The 'Uprated' switch is better anyway as the span is just a few degrees opposed to the 9 degree span of the standard which is what leads to melting fuses.
Also it's worth rewiring the fans and checking the voltage at the fuel pump UNDER load (You want to be seeing alternator power ideally but so long as +12V is maintained. Plenty of info on the rewire on here, wiring is DIY or can buy the looms pre made as well, these are two chronic weak points!
Martin