Gene,
Cool model.
Here's one way to shape the wishbone back, using the native SketchUp tools:
Think about how you would make the piece in the shop: Probably cooper a blank, then bandsaw the shape. The SketchUp routine is similar, but since there's no bandsaw tool in SketchUp you'll intersect two shapes and erase the parts you don't need.
Begin by drawing the wishbone shape at its maximum thickness. It will be easier if you do this so the shape aligns with the red and blue axes. Make the shape a component. Then use the 2-point arc tool to draw the curve. Do this on the side of the wishbone shape, making sure the wishbone shape is not open for editing. Use Push/Pull to push the curve shape through the wishbone. Double-click the curve shape, go to edit>cut. Double click the wishbone shape and go to edit>paste in place. Single-click the component, copy it, and use the scale tool to enlarge the copy 100 times. Now, work on the giant copy. Double-click it, select everything, then go to edit>intersect faces>with selection. Erase all the waste. You should be left with a curved and tapered wishbone. Delete the giant copy and use the zoom extents tool to get back to the original component. Now you can rotate it into position on the model.
Hope this helps.
dh