IDK about where folks who can afford a "restoration mechanic" get their parts, but it appears that the brackets on his shroud came attached to it. Even with my 1965 shroud, meant for the 2524984 3 row radiator, 22", the steel shroud bolts to its brackets, which are bolted into the side of the radiator via 1/4"-20 bolts with suitable "cage nuts" placed inside the soldered on frame about the core. The pics provided above by SGVert show SUPERB work, with what look to be plastic anchors inserted into the radiator frame in place of cage nuts.
I MADE A NEW SET OF BRACKETS OUT OF 2" X 2" X 1/16" THICK ANGLE ALUMINUM, which were needed for the US Radiator 4 row radiator I purchased this past spring, anticipating the very record heat we got. I carefully measured exactly where to bolt the aluminum onto the shroud, as the old heavy stamped steel brackets were, and consequently got a more airtight fit for my shroud. Gertrude NEVER got warmer than 200 Fahrenheit this summer, which is the exact temperature I set the pusher fan to kick in for cooling things down to just ~196 degrees.
I removed my 7 blade salad chopper two weeks ago, and will leave it off until late May. If you want to see the way I put the angle aluminum on to secure my shroud, I'll post a pic or 2.