I have sheered all 4 pins, and every time they sheer, I replace them with a grade 8 bolt. Not a single issue in 4 years. I use a Nylock nut and then I use a dremil and round off the bolt head once it is tight so it fits in the perch.
You can step up to the next size centering pin if you drill out the leaf springs. Check the head fit into the spring perch before assembly, you may need to grind the head down a bit.