[b-man]

It’s been done.

I had a 1967 GTO here some years back where they did that. They extended a short support to fit the tall radiator. Kinda ugly but it worked.

Unfortunately the core support hung way below the bottom of the bumper. Unless you go the extra mile and modify the bottom with something substantial like 1/8” flat stock to eliminate the upside down channel on the short core support you already have to make the bottom flat like a factory 17-1/2”’support. All that fabrication will be spendy unless you have a good friend who’s a decent welder/fabricator.

Why don’t you try posting a want ad for the core support? If you had done that awhile back when you were considering this you might have found one already.

So it’s not like you can’t do it. But be aware of the ground clearance issues it presents if you don’t make the bottom flat.

Honestly there’s no easiest thing to do save for finding an original support that I’m guessing you haven’t looked for yet. It’s not impossible to find unless you give up before trying to find one.

Solid enough response?

Now cue the guys who are getting by fine with the short 15-1/2” radiators……which the factory didn’t see fit to use in the 1964 389 GTO……and of which the thread starter here doesn’t find adequate.