74 power wagon dream truck...

You will absolutely have to drill those rivets. I think a whole new assembly is available at rock auto. An even better way to go would be with Jungle Jim’s Fabrications. He makes a real nice mount/ bushing setup.
$$$$...:BangHead:.... LOL...
I assume the rear shackles as well? At least those I think I can put on my press....
I bought bushings for the frame from Summit but they don't look correct...