Then you should do the 4L80. It won't help track times because of the insane amount that it weighs, but very durable. Are you aware how heavy one is?
And now you're talking if you're going to turbo it. You're going to be in the inner fender guy club with me if you intend to drive it a bundle with a turbo - turbo, rain puddles and no inner fenders means lots of exhaust leak repair continually.
Is this going to be a DIY build? Costs can skyrocket if you have to pay for everything to be fabricated. Not that there is anything wrong with that if you can afford it and are willing to spend it. But you can save a pile of $$ if you can cut, grind and weld - the turbo build requires a bunch of that.