Yes it will and with some(Quite a bit to be honest) power to spare.
I honestly thing it would be HARD to get the system to pull 420 watts with that hardware.
I can JUST pass 350 with OCCT stress test(the PSU one) one a 2600K @ 4.4 and 5870(both take more power)
You must mean capacitor aging over time for the power supply(lowering its output rating to 420 not increasing its draw to 420). Honestly I think it will take a while for it to happen, but yeah. I guess it would reduce over time. My bad if the above looked negative towards your post.
I plugged those details into the eXtreme Power Supply Calculator Pro, made a couple guesses (regarding your overclocked Vcore and the rpm of that hard drive), and it gives a recommended psu wattage of 333 W with 23.2 A on the +12V rail, so a Corsair CX500 should be plenty.