The good news is they got back to me almost immediately.
The bad news is they said they won't sell the shroud separately, just the fan.
I happen to have a fan and shroud here, exactly what is shown above, brand new in the box from my personal blazer project I would sell you for the difference plus shipping. That would leave me in the same scenario as you in a year or two, but I'll make do.
The cooler you have is the largest one I've fit on a square behind the grill, especially with AC. Its 67,000 Btu/hr
A typical 6 pass tube cooler is only 6,000 Btu or so!
Another option since you are not trying to fit it between the grill and the radiator anymore, you could do something like one of these two, they are much thicker.
If you aren't restricted to that thickness, those two racing coolers below are 95,000 and 125,000 Btu/hr
The upper one is dual 5" fans, the lower one is a single 8" fan for size reference. The lower one is the 125K Btu unit. The also offer it with a slim fan thats 625 cfm vs that fan at 750 cfm.
I can also get Afco, Fluidyne, and Setrab (never heard of it) among others....
If you want the shroud/fan I have here let me know.