You can get heads that are called "Vortec" and will work with a conventional manifold, but they won't be genuine GM Vortec heads. They'll be made by Jimmy-Crack-Corn Induction Systems or Ah-So Industries or whatever and in my opinion, are a waste of money. None of the knock-offs have shown me that they flow anywhere near the original 12558060 GM heads. Having to use a dedicated manifold is a small price to pay in my opinion.
Knowing nothing at all about EFI and the new electronic systems and unwilling to learn at my age, re-wiring for a computer-based system sounds to me like a nightmare. I guess if I were going to do it, I'd buy a donor vehicle and install all the wiring from it to my ride, ripping out all the original wiring. I'm told there are companies who specialize in wiring systems to do it, but they won't be getting any of my money.