I have no experience with standalone EFI, but if you have the flexplate and MSD 6-Hemi (p/n 6013), the MSD harness that is applicable for your application (p/n 88863 for '05 running carb), + the fueling of your choice, you are good to go. The build above that I built the intake for, all I had was a complete engine with no harness's, and the only parts I bought were the MSD and the flexplate to make it run.