If you don’t use a roller cam, break the engine in on a known good carburetor and make the efi switch afterwards. There will be lots of cranking. Especially on your first go round.
If you just throw the EFI system on and try to start it that might be true. If you check and double check the electrical side of the install and go over the manual for whatever system you choose you shouldn't have any trouble. I know people that have installed Fitech, MSD-Atomic, FAST EZ, and Holley sniper systems and they have all fired off first try. If it is a more involved system like megasquirt or something just a little research will help with your startup tune. Mine lit right off and idled like it had always been injected, I actually wasn't ready for that I was ready for a fight lol.