I'd be weighing more SC the 370Z vs buying the new Z and building that up.
With prices these days, if you are in line for the new Z, you should come out ahead financially doing so, and have a nicer interior and longer warranty.
Shifting weight back will need a dry CF hood and fenders, removing AC, and relocating the battery, while keeping everything in the rear heavy. At the track, you'll be faster just making the car as light as possible. The extra few % really isn't that impactful at track speeds, and for balance, it is negligible with good car setup.
I was really close to doing so myself and just swapping all my track parts over.
Inertia with the existing car kept me from doing so, but it was close. Labor with how busy I am currently in life plus them switching to EPS were the main detractors, but it's still a decision I revisit from time to time.
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