Bronco front coil spring tree

if you can't get to the otherside, 'nutserts' but any grade of stainless should do after all you're replacing rivets...so although weaker than cold rolled (CRS) grade 303 non magnetic or 304 magnetic will do...anything that won't rust will be okay, still concerned with your access to the far side, that's why 'nutserts'...if they can be had in a screw size that is appropriate. Also may need some clearance, as rivets are lo-profile and am unaware of clearances needed....okay like it's an anchor for the spring shackle...right, Should never interfere with a bolt head...ya think?