I'm looking for a brushless DC motor, and the budget is not a problem.
There aren't too many brushless solutions with that level of torque (no real reason to limit yourself to brushless "DC" motors--they are simply permanent magnet AC motors with a built in trapezoidal inverter).
The brushless setup I know of that comes closest to those numbers is an AMR dual stack Remy core motor, pushed to its 600A limit. That will get you about 825 nm.
Now, you COULD push those motors past their current limits: Remy has some level of margin that they have built in. But, you certainly would be voiding your warranty, and would have a real chance of ruining your motor (they aren't like series wound DC motors in which you can push them many times their spec for short periods of time). What I would do is to go with a 700V system at 600A, which would extend that 825nm out to 7000 RPM, and then adjust your gearing to give you the torque at the wheels that you want.
Good thing budget is "not an issue". The two RMS PM250 inverters you'll need will set you back 25K, and the dual stack AMR motor will cost another 20K.