N650 is taken. It's currently assigned to a 1989 Combs Michael JK-1 LARK registered in Dallas, TX.
See the full aircraft record →A tail number only frees up if the owner deregisters the aircraft or moves it to a different N-number — and even then the FAA holds it before releasing it to the public.
N650 has been worn before. Past registrations from FAA deregistration records: