After stripping the window trim, I cleaned out any loose wood and dirt. Using Minwax wood epoxy filler I smoothed everything over with about 1/8 inch of epoxy. Then to avoid using several can of filler, I installed some filler pieces of wood. Then two more coats of epoxy to get things up to finish level and blended in to the undamaged surface. Finally some sanding with 60 grit followed by 120 grit and the sill was as good as new.
Next a prime coat and it's ready for a finish coat.
And a shot of the next section finally finished. This section went faster with out any soffit to replace other than just the crown moulding. Now I'll set up scaffold and catch the other outside and inside corners of the bump out. Should add to the learning curve!