Definately get ahold of Red Regal T. I believe he is doing a transplant into a 78 El Camino. I'm personally going to turn my 79 into a propane powered turbocharged 350.
The 84-85 motors didn't make as much power stock, as they didn't come with an intercooler. They also use a different intake, turbo location, MAF sensor, computer and so on. Some people think it's better to start with a later model vehicle, some think the hotairs are a hell of a bargain.