I went port EFI on a 505" stroked 440.
Originally the biggest issue was the fuel supply.
The remote sump as shown earlier in this thread is a decent solution if you have the under hood space.
For my '69 Coronet, I currently have the Spectra Performance CR9CFI Fuel tank that comes with a Walbro GSS342, 255 lph internal pump. Bought it from Amazon ($366.02.) Just check the terminals on the inside of the sending unit to make sure they are not shorted. This seems to be an assembly issue as I am not the only one who had this problem.

One of the nice functions of the EFI is full control of the ignition timing. This is where you might find increased fuel mileage, and better idle quality. At idle/no load you can advance the ignition for a nice idle, then under load it backs down to prevent pinging. At speed, it will also advance/retard the timing based on load and RPM to what ever you program.

Use a system that uses a wide-band O2 sensor. These are usually self tuning too.

Other functions you should look for is A/C clutch input so the computer know to compensate the idle for when the A/C kicks on, and if you plan to use electric fans for cooling, an output for the fan control so the EFI computer can switch the fans on/off.