swap graphic card (5670 out - 6770m in )

Hi all and thank you for your fantastic guides!

I already successfully replaced a burnt AMD 5750 with an AMD 6970 graphic card in a 27" IMAC MID 2010.

Now another friend of mine has problems with his

27" IMAC MID 2010 equipped with AMD 5670. (vertical lines, artifacts, random crashes when playng 3d games).

He is on low budget now, and wants replace his 5670 with a 6770M... is this one also compatible with his mac?

Many thanks for your help!

Antonio