Can I fit a 105 crank arm (stages) to a Claris 2400 crankset? I currently have a Specialized Secteur with a Shimano Claris 2400 crankset (compact). I'd like to buy a Stages power meter but they do not sell Claris crank arms.

Can I simply put a 105 crank arm on a Claris crankset?
Not a modern 105 - Claris cranksets are octalink, 105 cranksets are hollowtech.