The bigger the motor, the more streetable it will be, and the fastest under your restrictions. You have a beautiful ride there, do it justice with a very good build and stretch the budget to the minimum good parts your chosen engine builder wants you to run. The great thing about a 512 is it will have the most torque down low, and the car will pull like it has 4.10 gears in it, even though it has 3.54s. You will not regret this choice.