The A-12 was one hell of a s**tty design that was even less suited for carrier use than the commonly derided F-111B. Basically the navy had no idea what it really wanted (Hint: A stealth strike a/c does not need to have AIM-120's for self defence since the whole point of LO is to not be detected, and especially when these requires bays to be cut out in the most highly stressed part of the entire airframe. Also the need to carry 24 Mk82's internally is a ridiculous demand).
Also even if the A-12A had met it's 40.000lbs weight limit it would still have lacked a waveoff capability, so I'd wager the flight characteristics are quite accurate. It should basically be a suicide plane to land on a carrier as you only have one shot.