it is against federal law, and I highly advise against it.
However, if you're in a state that doesn't test emissions, then you should be fine.
I have a 66 mustang, and "technically" by law I'm not allowed to remove emissions components. However it is not subject to smog checks any longer, and no way in HELL am I ever going to put a smog pump back onto it.
However, going efi TO carb is drastic. Take the time to Learn efi. EFI is SO nice. I finally got my 66 running for the first time under dinasaur technology (aka carb'd) and it sucks. ALthough it's cheaper....It's going to take me a million years to tweak and tune that carb to where it even feels close to EFI.
I'm spitting distance away from pulling the trigger to go TO efi on my 66.