I have the exact same radiator (or the 31"-wide version). But I can't weld aluminum.
So what I did was build a rail (with a 30" piece of U-shaped aluminum) that fits inside the U-shaped underside of the rad. That rail bolts to the lower rad support with 2 L-shaped brackets. Felt liner alonside the rail.
Two aluminum brackets riveted on top of the radiator bolt through the upper rad support (in existing holes). I had to add a small piece of tubing as a filler between the top of the rad and the upper rad support (to prevent air to flow around the rad there), so the two brackets are riveted to that filler, whish is itself riveted to the rad core's top.
Here's a pic of the rail :