Try to turn the crank by hand. Depending on how long this has sat, the belts may need to come off. If the motor is free, check the oil. If it's up, pull the coil wire on the distributor, put in a fresh battery and try to turn it over. If it turns over, it might not be a bad idea to pull the spark plugs and shoot a little oil down the cylinders. Put the plugs back in and leaving the coil wire off, turn it over for 8-10 seconds 2 or 3 times to get the oil up on top of the motor. Put the coil wire back on, dump a SMALL amount of fuel down the carb, and turn it over, making sure the choke is fully closed. The fuel is the other issue. Gas goes bad after a year or so of sitting. You will probably have to pull the tank, drain it and the lines, rebuild the carb, and try it again. Sitting for that long may require additional work on seals in the tranny, etc. By the way, weren't they Mark V's by 1977?

Cars have sat for alot longer than 31 years and been in fine shape depending on where it is located. If you are next to the ocean and the car has been sitting outside then rust will be the issue. On the other hand if it has been sitting outside in Arizona it will not be rusty but the interior is going to be shot. Why not try to start her up, thats half the fun!