Carburetor, MSD, Holley Sniper EFI questions

I second 67 gt. If you're not up for it, moving over to efi is a bear. I did it on my Coronet, been running FiTech for 3 1/2 years. The terms "plug n play" and "learns as you drive" are marketing slogans. If you try installing and tuning the system yourself you'll end up joining about 1/2 dozen forums and scrolling through hundreds of pages of posts to learn why your car i) won't start cold, ii) won't start warm, iii) won't start hot, iv) suddenly dies while driving down the freeway, v) surges at idle, vi) dies at idle. I could go on and on but you get the idea; and that's post install. Before that you'll have drop the gas tank, upgrade your fuel delivery system from stem to stern, possibly upgrade your charging system, figure out how to get power at both start and run, figure out your ignition system. I'm just getting warmed up.
I know there are scores of enthusiasts that love their efi, and just as many that despise it or went back to a carb. A lot depends on how you use your car. If you drive a couple thousand miles a year mainly to car shows and around town, stop and consider if the time, money, and learning curve are worth it. If you do decide to go for it, this is a great forum to be a member; lots of guys have had success with their efi installs.