What do you estimate the weight of the car will be when done?

I would go for a gear in the 3.00-3.2X range if you stick to your gameplan for powerplant. The torque will pull the gear, even with the 6 speed. No worries there.

The length of the gear will help the car have a bit more managable of a powerband. Still not easy, but manageable.

If you plan on doing ANY roadcourse work (REAL roadcourse action, not drive around the course point it straight and shoot) then realistically the oversized turbo plan is the one for you.

An electronic boost controller will do no good, as boost will only go as low as your wastegate springs allow generally. If you run anything more than a 4-5 psi gate spring, which you likely will, then the setup will build more torque at low rpm then you will plant regardless if there is any steering angle applied.

That's where the larger, laggier turbo setup can be your friend. It may just be late enough that you can learn to drive with it as you come out of the corners, much like the old school turbo Porsche guys do.

Otherwise, some EMS systems such as AEM or Motec (I'm sure others, just haven't dealt with them as much) will have a VSS dependent boost function. The low end torque will still be there, but that would allow you to pour the power on the straight hard as the speeds increase.

Why E85? Just for fun, or is it readily accessible for you and cheap? There's nothing wrong with it in the least, it's great. Just make sure whomever is behind the keyboard has a good understanding of it, and knows how to calibrate your WB02 sensor for it, or adjust accordingly. Ask Josh about that.