Replacing FSA Mega Exo with Shimano RS500 crankset
Road cranks have spindles long enough for 68mm BB shells plus external Hollowtech bearings. The Jamis has a 68mm bottom bracket shell, so the RS500 crank will fit the frame. 

Make sure you get a 'road' BB for 68mm shells not an 'MTB' BB for 73mm shells, or 68mm shells with spacers. Those are too wide for the crank spindle.

Presumably the RS500 crank has the same chainring sizes and crank arm length as the FSA, so there are no problems there.