I have installed a few retrofit EFI setups ranging from TBI self learning plug and play to full sequential multi point conversions. For the look of OE, quality of aftermarket support, tuning capability, and expanded capability should you want it, look no further than the Holley Terminator Stealth. If you get one with transmission control and want to add a 4L80E down the road, you're covered. Want to have the ECU control timing, in addition to fuel, you can do that too. Fuel system, you can keep the stock tank and run an EFI surge tank, or convert to a drop in EFI tank.
I'm currently building a hydraulic roller square port 496 for a 68 Chevelle. Owner is going from a 396/TH400 to a 496 with Holley Terminator Stealth and a 4L80E, Holley will be controlling fuel, spark and transmission.