Ok....so I guess what I found was a chinese "knock off" of the edlebrock intake.....now I have to wonder if it is worth the $135 gamble or just go straight to the real thing......
Remember the old Fram filters adverts? Pay me now or pay me later. If you purchase questionable Chinesium crap made of recycled Yak turds, you get ****. Plus you are supporting a communist country that is adversarial not an ally.
Bite the bullet and get an Edelbrock made manifold. I would recommend the AVS2 500 carb also. Those will work real well for you on that beautiful car.
Regarding the 8.75" rear swap, I doubt with a 273 that you would hurt the stock rear, unless to get the 4.5" bolt pattern.