No FEA is necessary. Contrary to popular belief. A lot of good analysis can be done with a book, pencil and a napkin! All good ME design books will have a reference to Stress concentrations. They are generally relatively simple to use as long as you can read a chart.
Engineers edge (
www.engineersedge.com) is the 1st pass that I usually take when I'm looking and I don't have my book handy and the internet is available. Here is the section on stress concentrations:
http://www.engineersedge.com/calcula...tion-shaft.htm
This won't give you the stress unless you know the rest of the numbers, but you can at least compare Kts for the known geometry to determine what has less of an impact.
Shigley's Mechanical Engineering Design is my text book of choice. It was required in my college ME Design class. It is still something that I use regularly and has a lot of great references.
Good luck!