Ya' might think I'm crazy (wouldn't be the first) but try this. Drill a hole in similar sized stock. Put a thin layer of plastic (like Saran wrap) on inside of hole. Fill hole with fiberglass (resin or gel, not bondo) making sure the bottom side is covered to keep the goop in. When all is set (important for all to be really set) you now measure for the new "correct" hole so you can change from a push-bore to a draw-bore. Now drill through the wood and fiberglass (clamps and a drill press may be in order). You should end up with an arc shaped piece of fiberglass that can fit into your existing problem hole. 'Course if you can get you scarf joint apart do the same thing but without the plastic wrap - I had it in there as a mold release. This should get you a strong bearing surface with low crushability. I'm sure there may be more elegant solutions though I would worry about a wood plug working its way out as you drive the pin. Good Luck!
