So many options and reasons for doing it or not. On the 403, the popular choice was the Edelbrock Performer (not the RPM version) and the original quadrajet. It lightens up the front, gives a little improved flow and simply fits as it should with shaker and air cleaner. Anything else and you start chasing your tail with custom parts and mods and a shaker bolted to the hood when it doesn't work out.
