The later units are excellent (aside from the computer controlled models). They have many nice features not found on early carburetors. I use a 1977 carburetor on my own engine, outfitted with an electric choke for instant cold starts and fast idle during warm-up.
The later carburetors are often passed up because they are emission calibrated. With the right knowledge and parts they are actually better than early units for high performance use....Cliff