When I did that 4x4 conversion, I drilled through the rivets to get the spring mounts off the doner chassis. went just a little smaller so I wouldn't mess up the holes, then ground what was left of the rivet head off. used a chisel & heavy hammer to finish the job. Just an Idea..

I know a lot about a lot of things BUT I still have a lot to learn.
Life is what you make of it. So, why not make a working machine to make it easier.