I'm a little taller than you, and about the same weight. Depending on brand, I wear either Large or XL jerseys.

Different brands size differently, and then you have the 'Club Cut' and 'Race Cut' issue, which complicates matters.

You want it tight, so it wicks up and evaps the sweat better. Slightly more aero too. A full length or 3/4 length zipper is a big plus in hot weather.