What tool did you find worked best for deburring rivet holes in the firewall? For edges and large holes, sandpaper works fine, but I haven't found the right approach for rivet holes yet. I tried a cone shaped stone (for a die grinder) chucked into a slow drill, but the stainless just ate it up. A drill bit was moderately successful, although for freshly drilled holes with large burrs, it struggled to cleanly shave the burr off (same for my normal deburring tool I use on aluminum).
Did you find something that worked well?
Did you find something that worked well?