The Holley Sniper EFI is a relatively inexpensive system, but it gets a lot of good reviews. If I was buying an EFI system I think it would be at the top of my list. You also have the option of controlling distributor timing, but the Holley Dual Synch distributor add another $400 to the price.
Remember that you also need to figure out how you are going to set up your high pressure fuel pump and lines. Some folks switch to an '87 EFI tank because it has the baffles for an in-tank pump, but you still need a high pressure (not TBI) pump. One easier option is to just make sure the tank is always full so it does not starve either in in-tank pump or an external pump. There are also a couple companies that sell custom EFI-ready tanks, but they get expensive.
Its simpler if you only plan to use one tank, since you don't have to worry about how to handle switching.
Bruce