Center bolts for leaf dorings

The only really important thing is bolt shank size and head diameter, and of course length which you can hacksaw shorter. you can grind them shorter if needed, and actually grind the heads smaller dia if needed. Just grind "lightly" as if you were sharpening a knife, so as not to draw the heat treatment, and keep them cooled with dipping in water, etc.

Any good spring outfit will also carry spring clips / clamps