Power plate works good, it's supposed to even out the distribution of airflow (and thus alky) to the cylinders, thus reducing the chance of knock. For the price it's worth it. If you don't have a chip in the car, I'd bet you will be very happy with a turbo tweak chip and matching injectors. The one Eric burned for me is spot on with the mods I told him, I really don't even need to adjust the parameters.
There's only 1 station that sells e85 anywhere within a half hour of me. It's totally worth it if you can do it. I can run 28psi with no knock on it alone, and I use a small nozzle with water/methanol mixed 50/50 just for insurance in the summer at 30psi. I never see real knock and I can melt the back tires from a roll.
The heads and turbo you're looking at are better than mine. My walbro 450, stock fuel lines, and 80lb injectors keep up fine with my setup. 80's may be a limiting factor for you depending on boost, I don't know. 120's will require ecm mods. Maybe someone else with the parts you are looking at can comment.