CPUs are made to last indefinently if you treat them right. I have an old 500Mhz AMD K6-II thats still going strong. I use it for some dev stuff, and its been on 24/7 for years now (it used to be over clocked way back when it was used in my gaming rig)
Just try it out and see. You can always switch back to 3.2Ghz. Run some bench marks, check the core temps. No need to panic for 70deg as long as it doesnt affect stability.
If you dont like the temps, clock it back down some, or invest in better cooling.