Thanks a lot for the help to both Michaels! Yes the curve came from Illustrator and I can see the sloppiness in the curve.

I changed it to sharp edges and the Fillet command worked as expected:


Rounding over the front edges was also easy:


After using Boolean Diff for the neck pocket:


I'm happy it looks like the real thing now!

I'm not so happy with your blend solution Burrman as it seems to add a "bulge" to the side. It looks not bad but guitar body sides generally are cut straight. Thanks anyway.