Yeah, shock bolt's one way to do it, kinda cobbed up IMHO, but works just the same I suppose.
I don't know how much a shop would charge for the welding, but I suspect it will be as much or more than the cost of the hotchkis pieces themselves. Strength who knows? I bet 3/16" would be stronger than the factory pieces. It's not a real critical part unless maybe it let go SCCA racing in the middle of a high-speed turn. Dunno.
Here's what I did:
http://stuff.is-a-geek.net/PhotoAlbum/Cars/Pics/duster_38.jpg