“Best” all around axle ratio: ~450hp w/ A904?

A 3.23 will kill that car. The tallest i'd go in your car is a 3.73. I've run them with your power level and it's a balance.

If and when an OD is in the budget you'll never go back. Running 4.56's with an OD at your power level is perfect.
What size tire with the 4.56?