Since the iMac is alo offerd with an 1156 form i7 2.8 GHz chip as an optional upgrade, I'd wager that at the very least THAT particular chip would work. The 2.93 part may work to, but the BIOS must support the part and that is up in the air. I'd say the chance of success for the 2.8 i7 chip is probably high enough to warrant a try though.
It'd be great to find future support for additional 1156 based chips inside too!