As bigtime pointed out, the EFI doesn't (ok... can but shouldn't) control the fuel based on live O2 information. If the car goes lean, the EFI is usually in "open loop" under full throttle. This means any lean/rich spikes WON'T be compensated for. Works just like a carb.

Also, anyone who thinks setting up EFI to work is easier then a carb is fooling themselves. Yes once you get it dialed in, changing A/F ratio is as simple as a few key strokes, but I can tell you that I've made 2 jet changes on my blow through carb, and it idles and drives perfect with that little effort.

As for the turbo, yes you have a ton of room for a T6. However, if you're going to use that motor, a T4 would probably work (just because it's only 358"). As others have suggested, get on some turbo forums.

The turbo information on here is sparse and you've got a LONG way to go before you start buying parts. No offense, but if you don't know the difference between a BOV and a WG, you're not ready to buy any parts. Don't take that the wrong way, it's just there is a lot to learn about turbo's that is a lot different from NA stuff.

Seriously though, you need to pick a real HP goal. That is the biggest problem that gets people into trouble. Saying I want to make 1200 or more doesn't help anyone point you in the right direction. Remember that you need a chassis, rear axle, fuel system, etc to support the power. Set a plan and stick with it. 1200hp is A LOT more then what you have now, and you certainly don't need a R5/P7 motor to make that happen. You could sell it off and be miles ahead with the project if you did something more conventional.

BTW... one word of advice, E85 is probably not going to work at the ice drags. It doesn't start very good at E85, and in the cold states it gets watered down to E70 just to get cars to start/run/idle right in the cold. I think you'd be better off sticking with pump gas and an intercooler. The cold air will work great, and you can make all the power in the world on 93 and a good intercooler.