I ask because...
I have a friend in a local VC who used a "67-70 Mustang/Cougar aluminum radiator V8 with left inlet right outlet" off eBay for about $200 and has had no issues with it. By the images, it looks about right and measures in as well. He did have to modify the bracket, and he said it was a tight fit but it did fit. The bracket mod seems easy enough and is mainly trimming off excess material and drilling new mounting holes to match up. Listing image pictured here:
Here's the backstory on the old radiator that was original;
It was leaking enough to need a top off after driving for just 15 min. It was previously repaired (poorly). The estimated repair is $250+ re-cored at a local radiator repair shop who has been in business for almost 100 years.
Aluminum electrolysis issues aside, the brand new $200 mustang/cougar radiator option is sounding pretty good right now.