One thing there, overclocking doesn't drastically affect lifespan so long as you don't do something silly like run it at 1.6v, anything up to 1.5v (which you won't hit anyway) will run without issue, with little affect on lifespan.
The CPU will be long since irrelevant before this voltage takes any form of effect, in addition the chip is selected based on ASIC quality, and how well it can handle voltages in contrast with performance. They're designed for it.
My brother is still running my old 2700k with a 4.6GHz OC, no issues at all.