'67 Core Support Interchange?

Looking for help on sorting out a core support question. On the '67 GS400 that's in my signature block, were there two separate radiator//core support options from the factory? A couple of the radiator companies that I'm talking to are saying there was a larger radiator option (28" core) for a '67-'69 GS... However, I was under the impression that these cars didn't get a 28" core until 1970.

So, was there a larger option for my car? OR is there a core support from another car that will drop right in but still support a larger radiator??

For context, the issue is that I'm installing a Jim Weisse 482ci motor, and would really like to use something larger than the factory-sized 20" core to cool it. Plus I'd rather not switch to a dual pass setup if I can help it.

Thanks in advance for the info fellas,
-Jared

 

All '67s had the small (narrow) radiator opening in the core support. The '68-up got a larger (wider) radiator.

 

Thanks Gary. I don't suppose that '68 core support will fit correctly into the '67?

 

No.... the frame rails flare out on the 68-up to accommodate the wider radiator.
'67 Olds Cutlass/442 frames also flare out for a wider radiator. Unsure when Olds started to do that.
Those of us with 64-67 Buicks are stuck with the 20" wide core radiators.
Your best bet is a 2 row aluminum radiator. They have wider tubes than the old copper radiators and will out-cool a 4 row copper one.
Here's a pic of the Olds frame:

 

Thanks a lot for the info Walt. That's a big help.

 

If anyone is cooling big power from a stroker motor with one of these '67 core supports, please reach out! I could really use a sounding board here as I try to determine what will cool the incoming engine.