I'm using this Cold Case 2 row with 1.25" tubes in my 79. Fits like original, other than needing some 4 core size radiator pads(or carve out your old pads to make room), since the tank is thicker than the original 3 core radiator. Otherwise it installed easily. It cools a lot better than my original 3 core radiator did. I had an overheating problem with the old radiator, even though I had it cleaned out and tested. The tanks are formed to the original shape and the aluminum is polished. Good looking and performing radiator. Very happy with it.
https://www.summitracing.com/parts/RAD-GPF18A.
I can't say about buying the radiator support bushings by themselves. I have bought the OER rubber body mount set which comes with the core support bushings. Maybe somebody else knows where to buy them separately. But if you feel you need to replace the support bushings, you might want to replace them all anyway.
Later, I removed those new rubber bushings. They hadn't been installed very long, and I found some of the "new" rubber bushings were already cracking, so wasn't happy to see that. I decided to install sub-frame connectors from Pro-touring F-body, and solid aluminum bushings are suggested when going that route. That was a big improvement, and those solid bushings won't wear out.
