Not too hard to put a carburetor on what you have, if you've already have an engine. I would at least want something roller to start with, even better if you can find one with a short front end dress, but really a trade off for ease of install for harder to find and more expensive.
As far EFI or carb, you can either spend the time to wire it up, or spend the time putzing around getting the carb tuned in - it's about a wash.
With HEI distributor, yes, it's one wire for ignition. The duraspark units are a lot less bulky, though. Could run duraspark, GM HEI, and your existing coil. Still have fuel and other things to worry about electrically.