4bbl Carb off 1965 273 Motor?

If you're not concerned about matching numbers, all those early AFB's will fit the manifold. The main difference is in the jetting. With today's fuels, that may need to be modified anyway.....
Mark

Original jetting is fine with todays fuels. As a matter of fact they run better than all aftermarket in my experience on a close to stock 273 4 barrel engine. I'm still running mine.