True about the aluminium vs. iron block choice. You can always sleeve an ally block if you find you're getting bore distortion.
The WI system will allow you to run leaner than the usual "pig-rich" mixtures that other turbo cars have to use. I swear, a lot of Supras and Skylines I've seen smoke like diesels under acceleration.
Just a small pointer, I personally didn't have a good experience with Fuel Injectors used for WI, because they jam after a couple of weeks. Fortunately for me, they jammed in the closed position, maybe because the fuel pressure tends to close an injector? However, there's no telling, you might get them jammed in an open position. Secondly, I never got a good spray pattern from them, even though I pushed them to 8 Bars.There are a few multi-hole types that are better, but only just.
I inject after the charge-cooler, so I'm personally using an air-assisted system that makes a very fine fog. Obviously, having an air compressor on board with a regulator is rather impractical. As for temperatures, you're right on the money! I've dropped charge temperatures from 75° to 34° using water at 25°C. It's pretty cool to see the boost pressure rise as the compressor is happier (6).
Anyway, keep us posted on what you're up to.
Out!
edit: I'm getting a bit of water in my oil after 20-odd hours of crazy amounts of water injection (15 kg/hr of water for 150 kg/hr air flow), so you've been warned! Apparently, it's the valve stems that carry water droplets into the oil circuit.
