I am more in favor of a sequential fire aftermarket port injection system like sold by Holley, Fast Fuel or Edelbrock.
A TBI is nothing more than an electric carburetor that still mixes the fuel and air in the intake manifold where it can fall out of suspension. It won't make the power of a carb and it will definitely cost you a lot more than a new Holley and intake manifold.
What you left off your list are the fourteen sensors that the computer will need to make it's decisions. There are more required than just the throttle position sensor and the oxygen sensor that you are probably aware of. The incoming air temperature is also required, the volume of air ingested, the absolute vacuum manifold the temperature of the coolant, and a knock sensor. In the tranny are also speed sensors and load sensors that give the computer feed back. Don't forget to buy a computer controlled HEI distributor with the TBI if go that route, as it won't work without it.
If you want to go EFI then I recommend that you replace the entire motor with a 5.3 liter out of an almost new SUV or pick-up truck. That little 324 can easily and reliably out put over 500 horsepower if you install a power adder of some kind. But even in stock trim it will output 270 horsepower to the rear wheels. It employs variable cam timing, and displacement on demand (turns off four cylinders when cruising to increase your mileage) in addition to port injection and great free breathing heads.
You can buy a complete motor and computer controlled overdrive transmission with the factory computer for the price you would pay for an aftermarket EFI set up.