I replaced the rear cross member on the Model A Ford. 1/4" rivets.
You need to have a good source of heat. A hand mapp or propane torch isn't enough. Oxy acetylene is best.
And you need a good air hammer or a rivet gun is best but expensive..I used an air hammer....
As you might guess there is technique involved. I found that too much pushing on the air hammer did not help. Its best to hold a little pressure and let the hammer do the work.
Some rivets turned out real nice, some not so nice...but they hold well enough.
Some more info and installation instructions here..
http://www.bigflatsrivet.com/Big Flats also sells a bucking tool....It worked well enough in the right places.
Here you can see the tool and a couple nice and not-so-nice rivets.